X'A020' QMR50 - UNLOAD - INVALID CALL SEQUENCE

Explanation
 Invalid sequence of calls to DFSQMR50. The error
is set if a GN call is issued for the next message buffer and no message
is being processed (GU).

Programmer response
 REG1 in the REG0-REG15 contains the call
type. REG6 or MRQUNLMC in MRQWORK points to the unload buffer. The
first two bytes are zero if no message is in progress. The prior message
returned on unload may still be in the buffer. The problem may be
that the last message contained incorrect first/last flags or an error
in logic between QCF and IMS.