Hi Mark
Have you checked, if the programm GRAC_ACTION_USAGE_SYNC and GRAC_ROLE_USAGE_SYNC runs correctly for the concerned systems?
Another possibilty is, that the interface user hasn't not the right to select the data. Watch on the connected system in the ST22, if there any dumps from the calling GRC system. Maybe the system user has to be authorized correctly.
I hope this help?
Regards
Martin