You need to trim/SEO the wall twice. They are two separate relationships the wall to the lower roof and the wall to the upper roof.
Trim the bottom of the wall by selecting the roof that cuts the bottom and crop element to base/subtract with downward extrusion
The second cut select the upper roof and the wall
crop element to top/ subtract with upward extrusion
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"