Problems with EPM add-inn

Hi

I am new to BPC and the EPM Excel add-in.

I have MS BPC 10sp10 installed and EPM sp14. I am looking at the Sample database and can see all dimensions

Creating a New Report, selecting Across and Down dimensions, pressing Ok, i get an error "The execution of report Default Report Failed."

In the Details it tels me "Internal Server Error", which is not very informative.

I must have done something wrong in the installation (or IIS setup), so if some of you have some guidelines where to look, it would be very much appreciated.

Regards

Allan