Publish message to RIB AQ from external system

We are trying to publish a message in RIB AQ ETEXTENDOR from IIB, We are able to put message in AQ, but somehow RIB subscriber -RIB_RMS_VENDOR_SUB_1 is not dequeuing that message. I have created dummy subscriber to ETEXTVENDOR, I see that dummy subscriber can dequeue the message. if i publish the same message in rdmt, it is processed successfully without any error message. Is there any specific format needs to be followed when you publish message through external system