Excel Web Access Web Part: Error:
"Access Denied. You do not have permission to open this file on Excel Services. Make sure that the file is in an Excel Services trusted location and that you have access to the file."
Solution:Besides permissions related issues, this error may also appear if you are attempting to display an Excel file that is stored in a separate web application where you have not enabled cross domain access.
To enable cross domain access for Excel Services, run the following command:
stsadm.exe -o set-ecssecurity -ssp SSPNAME -allowcrossdomainaccess true