Ok heres all that could of gone wrong....First off either of you could have entered each others number in wrong so double check that to make sure. Next, if both numbers are correct make sure the internet on both wiis are turned on because the Friends List data base has to identify that both of you have added each other so it can enable you to send messages to eachother. This could take a few hours after you have entered both codes by the way. Lastly, if all else fails, then you may not be conncected to the internet right and something could be wrong. If you can't figure out what is wrong then contact nintendo. Hope this helps!