[Serusers] AVP_DB_LOAD ERROR !!!

Hi ! I have a problem with this instruction: if(avp_db_load("$ruri/username", "s:callfwd/usr_preferences")){ setflag(22); avp_pushto("$ruri","s:callfwd"); }; avp_db_load instruction is always false ... in all condition (field of usr_preferences table are correctly compiled )! It work only in this condition: if(!avp_db_load("$ruri/username", "s:callfwd/usr_preferences")) nevertheless when the last condition (with a negation) matched avp_pushto instruction report this error "avp not found". 1) Why avp_db_load condition work only whit negation ? 2) Why avp_pushto report this error ? Thanks to all. A.C.