The corresponding coding in the function module PRICING_CHECK reads as follows;
IF komp-kposn = 0 AND komt1-kkopf NE 'X'.
MESSAGE e213 WITH komv-kschl RAISING no_head_condition.
ENDIF.
It looks in your case, since KKOPF field is checked you get error. If you remove the check as header condition, can you check what happens during testing?
Regards,