Seam not separating at sub model BC

[baudencm]

All,

I have a sub model that I've cut from a larger model. The shape is a square with the whole perimeter as the BC driven by the global model. I am then defining a seam from the middle of the left side into the center of the square (crack). For some reason, the node on the perimeter where the seam begins does not separate upon loading while the rest of the seam behaves properly. Is there a way to define a duplicate node at that location so the upper half of the square can separate from the bottom half?

Thanks!

CB