I already did it and it does not work
Please don't say this, this doesn't help the problem at all, what you are doing is just a gimmick to get more messages.You can speak to an appropriate staff member? Also, Try refresh your computer and your connection?
Having too many friends just adds to the number...How many friends do you currently have?
The -1 most likely means you have a friend too much in your list. You'll have to remove some in order to be able to add players again.