Null Pointer Exception importing WSDL / XSD file using SoapUI 3.0.1

I am trying to get experience with SoapUI using the WSDL for the first webservice listed here.... https://www.flightstats.com/developers/ ... vices/WSDL

I have downloaded the  AirlineService.wsdl AirlineService.xsd files which I've also attached but when I try to import the WSDL using SoapUI v3.0.1 I get the following error but don't know why. Can you advise please?

Tue Dec 08 09:24:48 GMT 2009:ERROR:org.apache.xmlbeans.XmlException: Thread SwingWorker: The 6th supplied input is not a schema document: its type is N=
  org.apache.xmlbeans.XmlException: Thread SwingWorker: The 6th supplied input is not a schema document: its type is N=
  at org.apache.xmlbeans.impl.schema.SchemaTypeSystemCompiler.compile(SchemaTypeSystemCompiler.java:211)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
  at java.lang.reflect.Method.invoke(Unknown Source)
  at org.apache.xmlbeans.XmlBeans.compileXmlBeans(XmlBeans.java:667)
  at org.apache.xmlbeans.XmlBeans.compileXsd(XmlBeans.java:553)
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.buildSchemaTypes(SchemaUtils.java:272)
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.loadSchemaTypes(SchemaUtils.java:182)
  at com.eviware.soapui.impl.support.definition.support.XmlSchemaBasedInterfaceDefinition.loadSchemaTypes(XmlSchemaBasedInterfaceDefinition.java:79)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlInterfaceDefinition.load(WsdlInterfaceDefinition.java:52)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlContext.loadDefinition(WsdlContext.java:66)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlContext.loadDefinition(WsdlContext.java:30)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext.cacheDefinition(AbstractDefinitionContext.java:264)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext.access$400(AbstractDefinitionContext.java:44)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext$Loader.construct(AbstractDefinitionContext.java:230)
  at com.eviware.soapui.support.swing.SwingWorkerDelegator.construct(SwingWorkerDelegator.java:46)
  at com.eviware.soapui.support.swing.SwingWorker$2.run(SwingWorker.java:140)
  at java.lang.Thread.run(Unknown Source)
Tue Dec 08 09:24:48 GMT 2009:ERROR:com.eviware.soapui.impl.wsdl.support.xsd.SchemaException
  com.eviware.soapui.impl.wsdl.support.xsd.SchemaException
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.buildSchemaTypes(SchemaUtils.java:282)
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.loadSchemaTypes(SchemaUtils.java:182)
  at com.eviware.soapui.impl.support.definition.support.XmlSchemaBasedInterfaceDefinition.loadSchemaTypes(XmlSchemaBasedInterfaceDefinition.java:79)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlInterfaceDefinition.load(WsdlInterfaceDefinition.java:52)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlContext.loadDefinition(WsdlContext.java:66)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlContext.loadDefinition(WsdlContext.java:30)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext.cacheDefinition(AbstractDefinitionContext.java:264)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext.access$400(AbstractDefinitionContext.java:44)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext$Loader.construct(AbstractDefinitionContext.java:230)
  at com.eviware.soapui.support.swing.SwingWorkerDelegator.construct(SwingWorkerDelegator.java:46)
  at com.eviware.soapui.support.swing.SwingWorker$2.run(SwingWorker.java:140)
  at java.lang.Thread.run(Unknown Source)
Tue Dec 08 09:24:48 GMT 2009:ERROR:com.eviware.soapui.impl.wsdl.support.xsd.SchemaException: Error loading schema types
  com.eviware.soapui.impl.wsdl.support.xsd.SchemaException: Error loading schema types
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.loadSchemaTypes(SchemaUtils.java:187)
  at com.eviware.soapui.impl.support.definition.support.XmlSchemaBasedInterfaceDefinition.loadSchemaTypes(XmlSchemaBasedInterfaceDefinition.java:79)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlInterfaceDefinition.load(WsdlInterfaceDefinition.java:52)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlContext.loadDefinition(WsdlContext.java:66)
  at com.eviware.soapui.impl.wsdl.support.wsdl.WsdlContext.loadDefinition(WsdlContext.java:30)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext.cacheDefinition(AbstractDefinitionContext.java:264)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext.access$400(AbstractDefinitionContext.java:44)
  at com.eviware.soapui.impl.support.definition.support.AbstractDefinitionContext$Loader.construct(AbstractDefinitionContext.java:230)
  at com.eviware.soapui.support.swing.SwingWorkerDelegator.construct(SwingWorkerDelegator.java:46)
  at com.eviware.soapui.support.swing.SwingWorker$2.run(SwingWorker.java:140)
  at java.lang.Thread.run(Unknown Source)
  Caused by: com.eviware.soapui.impl.wsdl.support.xsd.SchemaException
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.buildSchemaTypes(SchemaUtils.java:282)
  at com.eviware.soapui.impl.wsdl.support.xsd.SchemaUtils.loadSchemaTypes(SchemaUtils.java:182)
  ... 10 more
Tue Dec 08 09:24:50 GMT 2009:ERROR:java.lang.NullPointerException
  java.lang.NullPointerException
  at com.eviware.soapui.impl.wsdl.actions.project.AddWsdlAction.importWsdl(AddWsdlAction.java:129)
  at com.eviware.soapui.impl.wsdl.actions.project.AddWsdlAction.perform(AddWsdlAction.java:105)
  at com.eviware.soapui.impl.wsdl.actions.project.AddWsdlAction.perform(AddWsdlAction.java:55)
  at com.eviware.soapui.support.action.swing.SwingActionDelegate.actionPerformed(SwingActionDelegate.java:101)
  at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
  at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
  at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
  at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
  at javax.swing.AbstractButton.doClick(Unknown Source)
  at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
  at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
  at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
  at java.awt.Component.processMouseEvent(Unknown Source)
  at javax.swing.JComponent.processMouseEvent(Unknown Source)
  at java.awt.Component.processEvent(Unknown Source)
  at java.awt.Container.processEvent(Unknown Source)
  at java.awt.Component.dispatchEventImpl(Unknown Source)
  at java.awt.Container.dispatchEventImpl(Unknown Source)
  at java.awt.Component.dispatchEvent(Unknown Source)
  at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
  at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
  at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
  at java.awt.Container.dispatchEventImpl(Unknown Source)
  at java.awt.Component.dispatchEvent(Unknown Source)
  at java.awt.EventQueue.dispatchEvent(Unknown Source)
  at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
  at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
  at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
  at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
  at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
  at java.awt.EventDispatchThread.run(Unknown Source)