Shoutbox

So i have windows live messenger and at the start the webcam thing worked fine, but like a month ago it stopped working and ive been trying to find a way to fix this but the only thing people suggest is downgrading my msn version which hasn't worked for me... (tried pretty much every version available by now)
soo the problem is like this, when i click "show my webcam" or "start a video call" right away it gives me an message saying that the person i tried to start it with declined, i asked if they declined it or not and they all said that they never even got the invitation. and if someone tries to send me an invitation i can't see it either. help would be awesome :)