Trying to order the Ecco Pro program

I am trying to order the Ecco Pro program. I have created an invoice . I log into the http://eccopro.com http://eccopro.com/ website. It tells me there is one unpaid invoice. I click on the invoice and click on the “Pay Selected” button. The button dims for a while then nothing happens. I have tried using 2 different browsers without success.

 
 
 What other way is there to pay for the invoice? What other web site should be used?