Hi.
Check this new doc, with different values, and with the relese of standard cost and MR21 included in the month.
Exacly the same behavior, UMB of MR21 must be 0, and PRY is the difference between Standard and Actual.
http://scn.sap.com/docs/DOC-45015
PS. ML close of the previos month create 2 documents, one on the previos and the one for the beguing stock, you dont need to mix documents of different preriods.
Wish this clirify.
Arturo.