I m running a yahoo group now facing problem "group not found" msg appear why? unable to post or deliver the m?

whn try to post msg to the group, bounce back to my in box " unable to deliver your msg, group not found. try to moderate any mesg approve msg but not appear on group msg. check moderator activity found the msg have been approved or deleteed or rejected. complain to customer care but they are unable to track down the problem they are working for last one week but not solved. I would appreciate if any one could give me the feed back.