why does this happen when skinning?

http://i10.photobucket.com/albums/a1...kinproblem.jpg

as you see only on one soldier the shields transparency is not showing. this has happened on many units i have tried to skin, it only happens on shields and helmet plumes. i don’t get what i am doing wrong? and why is it only on one soldier?

i would be grateful if i could resolve this as it really holds me back