Exception: org.eclipse.birt.report.service.api.ReportServiceException

Hi following error occurred when i tried to run the report (using BIRT Web Viewer Example Webapp) through windows server. The Web server used is Tomcat.
 
I try to load the test.rptdesign report  
 generates following error.
 
 org.eclipse.birt.report.service.api.ReportServiceException: Error happened while running the report; nested exception is:
java.lang.NoClassDefFoundError
 
Please Help
Anoop