An error occurred during an attempt to read the federation metadata

HI,

I installed the AD FS 2.0 into Windows server 2008 R2 following http://technet.microsoft.com/en-us/library/adfs2-federation-wif-application-step-by-step-guide(v=ws.10).aspx. However, when trying to add relying party, an error comes up saying,

An error occurred during an attempt to read the federation metadata. Verify that the specified URL or host name is a valid federation metadata endpoint.