I cannot send or receive or ims.?

my friend and i are trying to chat through messenger. we send each other messages but neither one of us receives them. i dont get his and he doesnt get mine. i tried adding him onto my messenger list to see if that will fix the problem. he accepts the invitation and my messenger says that he has been added but then when i sign back on to messenger it says request is pending. i cant get him to stay on there as a contact. can someone help me?