Hi,
could you please share your message payload?
did you try putting prefix of namespace prefix also in the xpath expression?
check below one.
Also, I have went through certain threads which states that these filter criteria don't work in SAP PI 7.1 production server, Please provide inputs on the same.
check in below link for shabarish's reply.
http://scn.sap.com/thread/1966205
Regards,
Muniyappan.