Excel Services : Access Denied

You have done all the correct things to get that excel sheet on your web page, you have added the correct links in trusted file location, trusted data connection etc. But all you get is a lousy

"Access Denied. You don't have permission to perform this action or access this resource." error !

I hope these commands solve the issue
stsadm -o setsharedwebserviceauthn -negotiate
stsadm -o execadmsvcjobs
iisreset
Here is the link, Thanks to Ira Levin