"Die eingegebene Seriennummer ist ungültig" - Downloadversion CS2

Hy,

i bougt a CS2 Premium at ebay, because a Bro of me works with this version and he needs help sometimes.

When I install the CS2 with the CDs I cant activate it.

I got the information to download a version from the Adobe-Server an install it.

I do so.

But the serial-number from the adobe-Server don't work.

I get the error "Die eingegebene Seriennummer ist ungültig. Überprüfen Sie die Nummer, und geben Sie sie erneut ein."

I'm sure it's the right number! I fill in without blanks, with blanks and with "-"... No result.

Can anyone helb me with this problem?

Greetings

Harry