it looks like u have some things missing in your .skin file. Im not sure what screen you used as a template, but looks like u maybe deleted to many items.
I wouldnt follow directions from a plugin etc on how to set them up in this skin, as things are a lot different in this skin than they are in other skins. If you changed the button code on any of the dynamic buttons on menu.skin im pretty sure you just broke a few things. It may not be obvious but will likely popup somewhere down the road. The best thing to do would be to use the built in app embeder. Click and hold a button and choose one of the EMPTY buttons from the list (on 3rd Screen) then follow the directions. Should take like 2 minutes to do and requires no editing of any files.
as for your .skin file above.
you have some bad grouping that may be an issue. Try moving the A,0,42,800,394, to be on the bottom, or not in the middle of the Labels group. The plus minus labels are right under it and im guessing they arent being rendered cuz they are out of order, or its possible your A line is too big and is covering them up.
what does that app do? If its something a lot of people use its prob a good idea for me to include it by default.