SSO with multiple SAP systems

Hi,

I've configured SSO with a ECC system and a BW system to my BO 4.1 SP04 system.

Simple user names are set and same user names from both systems are merged.

So it's currently like XYZ user name is defined with ECC~100/XYZ and BW~200/XYZ.

ECC is set to default system.

When I want to run a report with BW OLAP Connection, it runs if I login with BW user info.

However it fails and can not even find the connection If I login with ECC user name.

Do I need to set a certificate or something between any of these systems?

Thank you!