Optional BEx query variables not working in WebI

Hi,

I have an Webi report based on Bex Query using BICS connection.

One characteristic is restricted with two variables. First an authorization variable and additional with an input ready variable.

This input ready variable is optional. When it comes up in webi and you choose a value it doesn't filter on it.

We are on BO 4.1. SP3 and BW 7.31.

If I have SAP_ALL the optional prompt is working, but for a normal user with limited access, the optional variable doesn't work.

Any ideas?

Thx and Regards,
Katharina