Wrong movement rigged cloth

hi guys. i need your help
I don’t have any problems on leg movement and syncin’ with.
But here :

problem on marked side.İn real there is a rubber on the waist side and it never moves.But here is it moves and shows THIS.How i can make the waist point steady when armature moves / runs/walks/looks up/down
If you need :

Got armature modification and no collisions etc.

I hope i could tell my problem.