installing upgrade from LR5.7 to LR6 problem

I've just downloaded and installed the upgrade (PC) from 5.7 to 6 without any problems . Then when I run the programme it wants to validate the serial number but it then comes up and states 'connect to internet to validate serial number' and won't validate.  Bearing in mind that I have not 5 minutes ago downloaded and paid successfully from the Adobe website this is annoying.  Now it says to contact customer services Monday to Friday between 9am and 5pm.  Unfortunately I'm at work during these hours so please how do I solve this problem.

Andre