DTC REPLY failing – what am I doing wrong?

I’m not sure how you copied your message so I can say for sure, but it looks like the DRVCTL metadata didn’t get copied form the original reply message to the new copy of the message, so you’re missing your DTC context.  We use DTC threads a lot, and whenever we copy a message, which is a lot in DTC threads because you need to take replies and change them them to data messages, we do these two additional steps:

set drvctl [msgmetaget $replyMessageHandle DRIVERCTL]

# DTC needs the DRIVERCTL from the copied message
msgmetaset $dataMessageHandleCopy DRIVERCTL $drvctl

The entire snipped to copy a DTC reply and CONTINUE the data message looks like this:

# Reply messages need to be copied to data messages in DTC flow; data message is sent on in the DTC flow.
set mhData [msgcreate -type data [msgget $mh] ]
# DTC needs the DRIVERCTL from the copied message
msgmetaset $mhData DRIVERCTL $drvctl
# set the code for messages with length > 6 to DONE, else QUIT the message
set message [msgget $mhData]
if { [some condition used to determine next state } {
set xCode SOME_STATE
} else {
set xCode DONE

}
lappend dispList “DTCNEXT {{$mhData $xCode}}”
# Kill the reply message prevent leaked memory/handle
lappend dispList “KILL $mh”