Sharepoint patch update issue.

I have Sharepoint server 2010 Enterprise edition installed in our test server. We have not installed any patch so far.  But i need to update to the latest patch 14.0.6123.5000 with June CU. So as a pre-requisite i need to update Sharepoint service pack 1 first.   But when ever i click the exe file, it gives me an error, "Error Occured While running detection".   The server is Windows server 2008.

Can some one help me on this?

Aravind