BP transaction user exit: what function module to read current BP data?

I implemented the BAdI BUPA_FURTHER_CHECKS to check data when BP data has been modified by the user, based on the country of the BP and the BP tax numbers that I get by calling respectively the function modules BUA_ADDRESS_GET_ALL and BUP_BUPA_TAX_GET. These function modules work well if I use the role 000000 (General), but BUP_BUPA_TAX_GET returns nothing if I use the role FLCU01 (CVI: FI customer). Why?