weird outcome with blendshapes

hi all, I need help since its been a while since I have used blendshapes. maybe it is something i am doing wrong. when I do my blendshape to roll up my sleeve on my character. I export it as usual from maya 2020. but when I move the blend shape value from 0 to 100, both sides of the shirt activate as well as move in, rather than up and scrunch up like a sleeve should. thoughts? I could really use the help in this to solve it.