Hi,
There is also a different way to view which SubVI is missing and where it is on the block diagram.
You can push the Run button of your main VI (even if it is a broken arrow) and a list errors window appears.
On the list you can view directly the missing VI or you can view all the VIs containing the missing VI as the "not executable VIs".
Choosing the specific error and clicking on Show Error button you can view where that subVI on the block diagram is.
I hope this helps.
Castel