Send Invoices/Billing Doc by Email not displaying:Urgent help

Dear SD Guru's

I have a problem where I am trying to send my billing documents by email. When I use the output type Mail and Medium 7, Program:RSNASTSO, Form Routine:SAPOFFICE_AUFRUF_VX and I assigned a form which was designed by one of our abaper's. The result is the when I sent the billing document, its is sent to the mailbox but the billing document which will now be a PDF file does not open. What could be the problem??

On the other hane if we use medium 5 External Send, the mail it is not sent, it remains in status WAITING, and remains in transit in SCOT.

I urgently need to your help, as this functionality is now overdue.