Proforma Purch order ssrs report (Document title is not showing the value)

Hello,

I created on new report for purchase order and it is working fine in every aspect except when I try to generate Pro forma Purchase Order report. When I run Pro forma Purchase Order document tile field is not printing "Pro forma Purchase Order" instead it is giving the text @SYS25550 in report (in Document title) . Can some one please help me with this issue.

Regards

Varun