Hi Janet,

Where did you try to run the application - Notes client or browser? Are you running it on local machine or server? 

This can be an signature issue so try to sign the database with your ID. Try one more thing - in your database where error is showing you can go to Domino Designer, in "Project" menu click on "Clean" - this would effectively recompile the XPages and Java code. It worked in case Thom.

Regards,

Naveen Maurya