Wrong Exchange signature

Hi all,

I'm looking to update my Exchange server 2010 farm with SP2 and I got a big surprise after running the Exchange Best Practice Analazyer.

I Got the following error : "Active Directory domain 'OURDOMAIN' has an unrecognized Exchange signature. Current DomainPrep version: 13040."

After a brief checkup on the web show me this : Exchange Server 2010 Service Pack 1 (SP1), the objectVersion value is 13040

But here's my problem : The version of my Exchange is 14.0 Build 639.21. So no Service Pack installed!!!

So, I'd like to know if can simply update the Exchange Signature (AD Schema) by running a DomainPrep with the setup of SP2?

If no, could you tell me what to do please...

Best regards,

Johnny