C$OSLockInfo not works with MF format files

We use C$OSLockInfo rutine to know which process is blocking one register file; the rutine returns the PID. It works OK with RM files format, but when we use it with MF files format, the rutine returns all 0.

Should we use the rutine in a diferent way when we use it with MF format files? Maybe we have to use another tool to get this information?

Thank you