Need Help with Blender for my SWTOR character


I’m looking for someone who’s familiar with Blender.
I have rigged a custom created skeleton for using in Source FilmMaker on Steam
But unfortunatly, i get a error, something about a “bone heat” when i try to merge the rig skeleton on the model for animating.

I tryed searching anywhere for help, but nobody has a clear-fix.
I wanna know steps to fix it. I’m kinda new to blender. I watched loads of tutorials about rigging and bone merging, but none gave me knowledge on how to fix this “Bone Heat” problem.

Here is a screenshot of the model:

Steps i did before it:

Now as you see its a custom swtor character. so what i did was getting the BodyParts and armor parts of the archive using EasyMYP and viewing them with the Noesis Program (with a swtor. plugin)
The files were in GR2. format, so i need to convert them to atleast obj. format.
Then when i got the right parts, i imported them all inside Blender and pasted them together and selected them all and clicked on “Join” to make them lock on each other as one model. i created the rig skeleton.

Now when i select the rig skeleton and move it (scroll around) the modle follows, but when i select the model, the skeleton doesn’t follow.
Normally in blender you must do “ctrl + P” and then “bone with auto…” but it says a error about the heat.