PDV onErrorOut issue

Hi all;

I'm using PDV service to call SAPQuery from R3 system, it works great using PDVJSPDynpage,

I want to change the Error messages from backEnd system but I'm having problems using onErrorOut function in PDVJSPDynpage class in case of wrong params that I'm passing to dynamic selection.

I also tried to use onJspErrorOut but still no luck !!

Is it possible to use this functions or modify them ?? does anyone have an idea how to show

friendly error messages to the user ??

thanks

Amit