Renew self cert but CA not trust SBS 2008

Follow this website to renew the self cert as below:

http://www.msexchangegeek.com/2009/04/24/how-to-renew-a-self-signed-certificate-in-exchange-server-2007/

Get-ExchangeCertificate |FL

Get-ExchangeCertificate -Thumbprint "Thumbpprint" | New-ExchangeCertificate

But I  noticed in IIS that the Certificate not trusted with CA.

OWA not trust.

How can i trust with internal CA server?

IIS Default Web Site can't start up normally.

Thanks.