RabbitMQ keeps logging
=ERROR REPORT==== 24-Aug-2014::06:25:07 === connection <0.109.6880>, channel 1 - soft error: {amqp_error,precondition_failed,"unknown delivery tag 1",'basic.ack'}
the log file is quite large.
You specified an invalid delivery tag that was already specified or never exists in terms of the current channel. See the application source code to find out how this happens.