Pop Up Message in Appraisal Form in Portal/BSP

Hi everyone:

I am using a BADI (Authorisation Check) for my appraisal form.

If the BADI encounters some authorisation error, it is supposed to pop up a message onto the screen.

If I just include the code "message w(001)zp" in my BADI, the BSP page that is displayed looks like a portal short-dump HTML page.

Can someone tell me what I should do, to have a pop-up message in my appraisal form (in the portal/BSP interface)?

Thanks,

Ash