500 timeout in AMQP Consumer #51

I am load testing using the AMQP publisher and consumer. I have two separate jmx. One is REGISTER Publisher that will publish to REGISTER QUEUE. Server backend will process the message and publish to RESPONSE QUEUE. Then REGISTER Consumer will listen to the RESPONSE Queue. However, i always encounter timeout 500 for the REGISTER Consumer when i load test. Any idea why the 500 error?