mouth movement problem

First step is to provie screen shots of the rigging hierarchy with the mouth part expanded out. Sometimes others can see it from there. Otherwise next step is to put puppet (using "Export / Puppet" from the menus) into Google Drive, Dropbox, or similar. Then share a link to the puppet here in the forums so others can download it. But its a bit hard to suggest anything without more information. There are LOTS of things that can go wrong unfortunately.