Hi there, hope someone can help explain this little problem I seem to have here.

So I've made a few models of pants, shirts, shoes etc.. which I wanted to use later in different combinations by merging them into one model and then animating.
Or even better I thought I'd make a bone skeleton on an empty model file, animate it, and then just attach merged models of bodies and easily make a small army of different actors with all of them having the same animations and not having to animate each one individually.

But there's a problem, even when I open just the pants model(already UV mapped) and just draw bones and try to attach vertices to it, it won't attach them.
Needless to say the attachment procedure doesn't work in any other combination (merging all models then merging or drawing bones, drawing bones then merging the clothes models onto it, exporting and importing models and bones.. nothing)

But when I just made a simple pole with a few sections, then drew bones it all worked perfect as it should so the whole program isn't flawed.

I guess the question is has anyone had this problem, is there a solution or maybe a specific order in which things need to be done? Or maybe the bones don't work on merged/imported models?