Generating PDF in Web-Dynpro

Hello,

I have a problem with generating a PDF file with ABAP WebDynpro. I have an ALV and there I read a line. From this line I want to build a smartform which should be converted into PDF. I think my coding works. I have no syntax errors and when I debug the coding, everything looks good. I also get my popup that I want to have. But then I got an error: "File does not begin with '%PDF-'."

I look for this error here in SDN but I could not find a solution. I have also tried to do what is mentioned in note 1042424.

Can anybody helps me?

Regards, Markus