Action check for "MODIFY SHIPMENT" action doesn't work in SERVPROV domain.

We have layout which allow to servprov change some shipment refnums. But we wants to avoid to change that refnums in some shipment statuses. We tried to set up action check for action "MODIFY SHIPMENT" for SERVPROV, but this action check doesn't work. Even if it contains impossible query (like "select shipment_gid from shipment where 1=2") refnums changes saves fine.

May be someone knows how we can set up action check on "MODIFY SHIPMENT" for SERVPROV?

Thanks for any help!