'Unable to export SWC oem'

i've gotten this error while monkeypatching* the flex framework. i'd googled for a solution, and though there is some help for this somewhat generic error message, it didn't solve my issue.

here's what went wrong in my scenario: i'd monkeypatched DataGrid.as, but forgot to bring over DataGrid.png. that's it: FlexBuilder was looking for an asset it couldn't locate.

* in our parlance, to monkeypatch means to make a change directly to the flex framework after moving that file to our CVS. note that in most cases, we monkeypatch in order to change private members to protected such that we can override behavior.