Hi Gianmaria,
I hope you are using OLAP Connections and managing through CMC in BI 4.0
Please check the Authentication Mode in your Connection Parameters whether it is selected as "SSO".
If yes, I request you to do the following test:
Step 1. Change it to " Use Pre-defined" and save it with User-ID and Password.
Step 2. Now Log-in with Enterprise and run the WebI.
If you are using IDT to manage connections, in Step 1, please select the option "Use specific User-Name and Password".
Please let me know.
Regards,
Krishnendu Roy.