We expanded a field and updated the DSV in BIDS once we did this the cube stopped building.  No real errors to report and sometimes it still thinks the field hasn't been updated in the DSV.  Have tried deleting the database and redeploying it, this didn't work.  The Problem still exists.  The cube will build in BIDS but it doesn't add data it stopped on the 9th of March.  Please someone help this is a critical cube and Im not sure what to do next.

We actually solved this problem today.  It's that heiarchy in the dates that was the killer.  Why it was triggered by a change in the dsv I don't know.  But its fixed and we are back running.