I came across this error while testing an orchestration. To explain the situation, we were pulling data from various tables via some stored procedures. We finally sent out a file, and then waited until an acknowedgment message was recieved. Once that message was recieved, we then called a seperate orchestration that would return a control number. Afterwards we would determine what kind of message to create based on the acknowedgment. It would then take the various messages from the stored procedure, and we would then have a map transform the messages into one single message.
This all seemed to work fine, until we would recieve the acknowledment, then it would label the call to the external orchestration as ’Delivered, Not Consumed.’

After banging my head against the wall for a while – a day of fiddling, etc – I took the call to the external orchestration out completely.
I then re-ran it, and it then labelled the acknowledgement as Delivered, Not Consumed, when I KNEW THAT IT WAS WORKING.
I then continued banging my head against the wall until I finally put a call into MS Support. I was quickly promoted to the 3rd level support, where I talked with an individual from England until he asked me to debug the orchestration. I then stepped through the orchestration, and I got past the consuming of the acknowledgment message, past a test, past a expression shape, and then it died when it invoked a map!
I then looked at the map, again, which took many messages, and created one message. It was not set up correctly, functoids were missing necessary parameters.
I then fixed the map, and the orchestration started working as expected.

So if you are reading this, please walk debug the orchestration if you ever get that message, because it normally means something down the orchestration path is bad, not the last communication outside of BizTalk had invoked.