armatures and weight paint

Hi im new to blender, and im animating a simply mouth with bones. But for some reason whenever I add weight paint to tell the bones what they affect, the mouth warps away. please help! its really annoying!

It’s best to post support questions in the support forums and also to provide a better description (with .blend files and/or pictures) because ‘the mouth warps away’ isn’t enough information to figure out what you’re doing wrong.