i know i've put the right username and password but it keeps saying incorrect ?
If you have fat fingers, slow down on the typing. I sometimes type too fast and my fingers would just hit two keys at once or have a delay of hitting the next letter before the previous letter could register. This happens through the WLO game, everywhere else is okay.
But if you can log in the site (browser), go to wl.igg.com from there. If you cannot see the credits on that page, or a line saying click to activate, click to activate so it will work.