First of all, some of your files are missing, C2 won't test for me...but...
Make your BG a little taller than your layout, say 32 pixels taller. Easier to turn on snap to grid.
Make a copy of that BG and paste it above your original. Making sure they both touch. Get the exact co-ordinates.
Backgroundfornow compare Y > greater/equal -32 > system create object > backgroundfornow (put the co-ordinates from the copy you made).
Also, delete your double post.