Auto roof return not working

[benmecham]

I've set all the gable walls to do an auto roof return, but this one (in the picture) isn't working. The wall underneath this roof plane (not the gable wall) has a small pony wall under it to get the roof to terminate at the height I needed. I'm thinking this has something to do with the problem because this is the only such wall in the house. However, maybe it has to do with the fact that this roof plane continues to the far right of the picture, where there is another gable end with lower eaves than this one (since there is no pony wall there.)

I hope that makes sense...
Please help me, it's driving me crazy!

Ben