Convert v4 key to licence file

I have a new PC and have installed Avast Pro. I also have a valid v4 licence key.

When I use the Request Conversion to v6 licence file option and enter my v4 licence key the screen flashes and nothing happens. No message and no subsequent email.

Any ideas on why this does not work or suggestions on a work around?

Thanks

How to Contact AVAST http://www.avast.com/en-gb/contacts