gta iv unable to connect to game session error HELP!

hello,

I need some help with gta iv multiplayer I'm trying to join my friends I can connect to anyone but two of them here is what we have tried

1.reinstalled gta iv

2.reinstalled GFWL

3. made new gamer tags with age over 18

4. submitted positive player review for each other

also all of our NATs are open, upnp enable and in use and the errors we get are unable to connect to game session or one of us is in a game and someone joins who we cannot connect to and we get kicked this has been happening for nearly 2 weeks and I have gone on also forums tried to find an answer (including foreign websites)

this is what happens when we try and join each other

I join and others try to join and get unable to join

they make game I try to join I get unable to join

I join another friend I join they try and get unable to join

they join other friend and I try to join I get unable to join

I'm in game and they join I get kicked

they in game I join they get kicked

anyone have any ideas,

many thanks