I was getting this before too until another kind DISer posted to clear your cookies and then it worked just fine. To clear cookies, Tools, Internet option, Delete Cookies, OK. Good luck!
Make sure there isn't an extra space at the end where you type it in. This can happen if you copy and paste. I've had it happen and when I remove the space, the code works.
Well.... I followed the instructions for clearing the cookies and I got in and got the points added, no problem! Thanks to the OP for the codes and the the person who posted about fixing the problem. Glad to add 50 pts to my account....................P