capability for RTP API

Hi,
Can anyone please tell me what is the capability needed in order to use rtp.lib. I am having a problem where once I call the following function in my application, I can't open my application in the phone, but if I remove the line, I can open the application successfully. It looks like the function is checking for a special capability.

RRtpSession* iRtpSession;

iRtpSession->OpenL(iSocketServer, localAddr, remoteAddr, 200, iConnection);

application capability:
CAPABILITY UserEnvironment MultimediaDD NetworkServices ReadUserData WriteUserData ReadDeviceData WriteDeviceData


Thanks

ok, turn out that the problem is RRtpSession library is not included in S60 release 9.1 and that's why it can't be run on S60 3rd edition release 9.1 phones.
It is advised to use the new RTP api (CRtpAPI). However, there is not much documentation there to guide you. Has anyone used CRtpAPI before and have success in using it?

Thanks!