The custom page is a selfsecured page?
ie, it will be accessed without login?
What is the profile option fnd_debuging_level 's value set to.
I Could see one your other thread
you mentioned that you did tried setting the profile options
Framework Validation Level
FND Function Validation LEvel
FND Validation Level
to none, still you are facing the issue,
At what level you tried the profile options.