My webcam doesn't work on msn?!please help?

i have an advent Laptop and the webcam is installed into my laptop it Works on everything else and ive tryed going to the control panel and properties and going to msn tools but nothing seems to work!!!!any help would be great :) also when i go to tools if says buy a webcam so im like :s but my webcam does work when some one sends me a request it works but just comes up with a grey screen with a webcam and a cross and no one can see me!!!thanks for the help :-)