Sometimes the AP section of the website is very difficult to log in. For one thing, they appear to take it down for a few hours every night, so if you are trying late at night or early in the morning, you may have problems.
Make sure you are selecting the correct "blank" AP to enter your data. I have the regular 4 park AP, not the Premium. I use the first one. If you ordered your pass by mail, you may have a voucher to be redeemed instead of an actual AP, so it's important that you pick the right one. If you try one and it doesn't work, try another.
If you have the actual AP, the data is at the bottom of your AP. I enter the three letter code first, for example, "WEC", then the exact number shown, for example, "089", then the date, for example, "05/03/08", and then the last number exactly as shown, for example, it may be from one to four digits long, so if it says "25", don't enter "0025", just enter "25".
I've never tried to do it from a voucher instead of the actual AP, but I would assume the procedure is the same - it's just a matter of finding out which blank you need to use.
