[h323plus] Null pointer reference

Hi, I am using H323plus v 1.26.3. With the External rtp example, I am getting a 'Assertion fail: Null pointer reference, file channels.cxx, line 629, Error=22' while trying to open a channel with capability G.711-ALaw-64k. it happens at H323_ExternalRTPChannel::OnSendingPDU at line number 1329.

Help appreciated