Form compilation gives error - declaration of the type of this expression is incomplete or malformed

Form compilation gives error - declaration of the type of this expression is incomplete or malformed. This is a working form in Production accessing a working database package.
Error 801 at line 1 column 1
internel error [1401]
declaration of the type of this expression is incomplete or malformed

Recent changes: Upgraded database from 9i to 10G (10.2.0.5.0)

System details:

Apps server - SunOS 5.10
Oracle DB: 10.2.0.5.0
Oracle ERP Applications: 11.5.10.2
Oracle Developer 6i patchset 19 (We are uptodate on the server side - I have tried to compile this form on the server - gives the same error)

Any help is appreciated.

Thanks

Rajeev Goyal