Why were you surprised, you did not look at FM signature (Exceptions tab) ?
CALL FUNCTION 'MD_PEGGING_NODIALOG' EXPORTING edelkz = edelkz edelnr = edelnr ematnr = ematnr ewerks = ewerks TABLES imdrqx = imdrqx EXCEPTIONS ERROR = 1 NO_REQUIREMENTS_FOUND = 2 ORDER_NOT_FOUND = 3 ERROR_MESSAGE = 4 OTHERS = 5.
Regards,
Raymond