FSXME mission loads but won't run.

First let me start by saying I am new to Mission editing/creating...

I have a weird problem I cannot figure out. I have created a mission that works but, not with the aircraft I want to use. I am making a bombing mission for the A2A B-17. Whenever I use this aircraft I can load the mission but, it does nothing no audio, waypoints or anything. If I switch to the default DC-3 it still will not work. The only time so far I have been able to get it to run is with the default Grumman goose. It has been driving me mad. If anybody can help. I am using FSX acc. I also used FXME to create the mission. My computer is brand new and built with FSX in mind and works well except for my mission. Also simvars is running and I do not get the simvars message. Thanks to anyone who can help.