Report output Format to pdf format

I am using Report Builder 6.0.8.8.3 and acrobat reader 7.0.0 version.
While generating PDF file from report previewer
using File->Generate to file->PDF option
it is showing message REP-0999 : Unimplemented Error.
Could anyone suggest me what might be the problem?

Try to use higher version of Report Builder.

Charater mode runtime incompatible with desformat of pdf file
so change the mode in system parameters to default or bitmap then
convert into pdf