Roof planes

[mjrsr0403]

I have two roof planes on the same roof on a house that I'd like to combine into one. I set them up to be produced as one with the build roof function. I've attempted to make sure the gable ends are equal and directly opposite, but somehow, they just don't merge.

A zip file with a jpeg showing the two planes is attached, along with the plan file. I've messed with this for hours but can't get it to work out. 'Any suggestions? Thanks.