Problem with calling the GUI email sending program from webdynpro

Hi Experts,

We have a custom program to release the PO,same program they are opening in enterprise portal through a tcode.Now we have enhanced the program to send the email after PO release.This program is working well in GUI,but this email sending portion of code is not working in enterprise portal.We are getting shotdump because it is containing GUI_UPLOAD,GUI_DOWNLOAD and cl_gui_frontend_services class and submit program to convert the PO out to PDF.I read in the SCN OPEN dataset also will not work.what changes do I need to  make his program work from portal?

Thanks & Regards,

Anusha.B