ACARS uplink format

[rampcongestion]

Hi all.
It seems the format for sending ACARS freetext message from a typeB address has changed recently.
we were given the following new format but i cant seem to get a mesage out, anyone got any better info for me?

=PRIORITY
QN
=DESTINATION TYPE B
STX,QXSXMXS-EI-XXX
=SUBJECT
=TEXT
This is a test message

Regards,
Frustrated OCC Duty Manager.