Simulator unable to locate Class in JAR file
 

We created a Blackberry project with 2 classes (A,B); then clean-built the project; packaged it to produce AB.jar; then preverified the jar file successfully; deleted the .cod, .cls. .cso files and created a new jar file. Then we imported the jar file into a different Blackberry project Z and successfully packaged the Z project. When we ran the new project on Blackberry 9800 Simulator, we got the error message "Error starting <project>: Class <package name>.A not found." We're using Eclipse Juno with Blackberry 6 SDK.
Why is the Simulator not finding the Class in the pre-verified jar file in spite of the fact that project Z compiled and packaged successfully?