I think the serial numbers you need should have been in the email which you received when you bought VPX4.
I have the boxed version and the numbers were printed on the outside of the DVD case. Having just checked mine I see it is a 16-digit number, no spaces. Is there any such thing in your email?
Sergei, did you fully unlock VPX4, by choosing the on-line or phone activation when you first installed it?
Sorry I can't be more helpful. Perhaps this is one occasion when you really need to talk to Magix sales.
Thanks for the additional answers. Has anyone with problems had any luck with a resolution?
I went back to Magix a couple of times now, always nice prompt responses, they also appologised for the fact I didn't get a serial in the first place, however they have now given me two seperate serial numbers (a string of 16 digits) and both times I have been greeted with the message "Serial Number is Bad" :-/ I almost feel bad going back again to say it hasn't worked yet again. I've sent them screenshots and a full description of my system and my process of installing the program i.e. turning off the antivirus and not having any other programs open. ...I haven't had any trouble with the other two free download programs.