microsoft.public.exchange.setup

I set up Exchange 2007 (32 bit edition) on my lab servers.
When I try to run the cmdlet for applying a valid license key (so that I'm
not using the 120 day trial) I use this command:

Set-ExchangeServer -Identity T-LAB-EXFE2K7.MYLAB.TEST.COM -ProductKey
ABCDE-FGHIJ-KLMNO-PQRST-UVWXY

The resulting output I get is this:

Set-ExchangeServer : Cannot bind parameter 'ProductKey'. Cannot convert
value "
ABCDE-FGHIJ-KLMNO-PQRST-UVWXY" to type
"Microsoft.Exchange.Management.SystemCon
figurationTasks.ProductKey". Error: "Invalid Product Key."
At line:1 char:70
+ Set-ExchangeServer -Identity T-LAB-EXFE2K7.MYLAB.TEST.COM-ProductKey <<<<
ABCDE-FGHIJ-KLMNO-PQRST-UVWXY

I have tried using both the Exchange 2007 Enterprise and Standard Edition
license keys, using upper and lower case letters, with and without hyphens -
and still I get nothing. It keeps telling me it's an invalid product key.

Am I missing something really obvious?

Dave