WsdlLoadTest cannot be cast to WsdlLoadTestPro

I have a pro license through the company I work for (can verify via message or however) and I'm getting the following error when trying to run a soapui load test from the command line using testrunner:

10:56:10,569 INFO [WsdlProject] Loaded project from [file:C:/load/Load-soapui-project.xml]
10:56:10,647 ERROR [SoapUIProLoadTestRunner] java.lang.ClassCastException: com.eviware.soapui.impl.wsdl.loadtest.WsdlLoa
dTest cannot be cast to com.eviware.soapui.impl.wsdl.WsdlLoadTestPro
10:56:10,647 ERROR [SoapUI] An error occured [com.eviware.soapui.impl.wsdl.loadtest.WsdlLoadTest cannot be cast to com.e
viware.soapui.impl.wsdl.WsdlLoadTestPro], see error log for details
java.lang.ClassCastException: com.eviware.soapui.impl.wsdl.loadtest.WsdlLoadTest cannot be cast to com.eviware.soapui.im
pl.wsdl.WsdlLoadTestPro
at com.eviware.soapui.SoapUIProLoadTestRunner.runWsdlLoadTest(SourceFile:88)
at com.eviware.soapui.tools.SoapUILoadTestRunner.runTestCase(SoapUILoadTestRunner.java:374)
at com.eviware.soapui.tools.SoapUILoadTestRunner.runSuite(SoapUILoadTestRunner.java:351)
at com.eviware.soapui.tools.SoapUILoadTestRunner.runRunner(SoapUILoadTestRunner.java:290)
at com.eviware.soapui.tools.AbstractSoapUIRunner.run(AbstractSoapUIRunner.java:149)
at com.eviware.soapui.tools.AbstractSoapUIRunner.runFromCommandLine(AbstractSoapUIRunner.java:84)
at com.eviware.soapui.SoapUIProLoadTestRunner.main(SourceFile:35)
c:\load>


any ideas?

Thanks, Ash