Trying to purchase Production Prem but the link is bad

I am currently working off of the trial and want to purchase however, every time the program has started and given me the trail window with the days countdown I would click on the buy button and it would take me to another page but nothing would come up. No when I open it I get the continue trial button or the option to enter my serial number. The buy button is now gone. How can I purchase to get my serial number????