SoapUIPro TestCase Runner Problem

I'm using SOAPUI Pro 2.5.1 and facing problem while running TestCaseRunner to test multiple test suite having multiple test cases simultaneously.  Test execution is working fine on individual test case level and this is only happening when I trying to run all at same time using TestCaseRunner.


Here is error I’m getting:

16:18:31,354 ERROR [SoapUIProTestCaseRunner] java.lang.NoClassDefFoundError: org/apache/xml/serializer/ExtendedContentHandler
16:18:31,354 ERROR [SoapUI] An error occured [org/apache/xml/serializer/ExtendedContentHandler], see error log for details
java.lang.NoClassDefFoundError: org/apache/xml/serializer/ExtendedContentHandler
at org.apache.xalan.processor.XSLTSchema.build(XSLTSchema.java:325)
at org.apache.xalan.processor.XSLTSchema.(XSLTSchema.java:72)
at org.apache.xalan.processor.StylesheetHandler.(StylesheetHandler.java:1290)
at org.apache.xalan.processor.TransformerFactoryImpl.newTemplatesHandler(TransformerFactoryImpl.java:376)
at org.apache.xalan.processor.TransformerFactoryImpl.newTemplates(TransformerFactoryImpl.java:867)
at com.eviware.soapui.impl.wsdl.actions.testcase.CreateReportAction.initTransformers(SourceFile:178)
at com.eviware.soapui.impl.wsdl.actions.testcase.CreateReportAction.a(SourceFile:122)
at com.eviware.soapui.impl.wsdl.actions.testcase.CreateReportAction.createReport(SourceFile:115)
at com.eviware.soapui.SoapUIProTestCaseRunner.exportJUnitReports(SourceFile:104)
at com.eviware.soapui.tools.SoapUITestCaseRunner.exportReports(SoapUITestCaseRunner.java:360)
at com.eviware.soapui.SoapUIProTestCaseRunner.exportReports(SourceFile:95)
at com.eviware.soapui.tools.SoapUITestCaseRunner.runRunner(SoapUITestCaseRunner.java:341)
at com.eviware.soapui.tools.AbstractSoapUIRunner.run(AbstractSoapUIRunner.java:127)
at com.eviware.soapui.tools.AbstractSoapUIRunner.runFromCommandLine(AbstractSoapUIRunner.java:72)
at com.eviware.soapui.SoapUIProTestCaseRunner.main(SourceFile:34)
Caused by: java.lang.ClassNotFoundException: org.apache.xml.serializer.ExtendedContentHandler
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
... 15 more

Does anyone know what’s going wrong here?