Hi,

Seems to me you suffer the double hop issue; Kerberos not enabled.

To solve this

Option 1:

Enable Kerberos Authentication

see http://download.microsoft.com/download/B/E/1/BE1AABB3-6ED8-4C3C-AF91-448AB733B1AF/SSRSKerberos.docx%5B/url%5D

Less secure and you use a generic account to access the data source

Option 2:

In ReportManager modify the dataSource credentials to:

'Connect using credentials stored securely in the report server'

Optionally set 'Use as Windows credentials when connecting to the data source'

Hopes this helps,

Regards Kees