Can anyone tell me why this won't compile?

[SMcNeill]

Line 11 is a typo.   You're getting your clear color for the 2nd image off a point in the first image.  It *should* be _SOURCE image(2) instead.  This is only working because apparently the two images have the same color associated with them.   Be careful of this.

Issue #2 that I see is that your _SOURCE remains to be image(2).  Be careful of this as well, as any future calls to point and such will default to it and not your active screen itself.

[bplus]

I feel like I should apologize for this rabbit hole I'm dragging you all down. 

What you are doing is commendable. Not only asking questions in Help me section but also posting your code to go along with your questions. You are probably helping several other lurkers who are too shy to get their selves setup properly with QB64. This is best use of this forum along with sharing fun things you've enjoyed.