rlm_sql: The 'Attribute' field is empty or NULL

Hi All I have this error in my log file : Sun Feb 16 09:17:57 2014 : Error: rlm_sql: The 'Attribute' field is empty or NULL, skipping the entire row. Sun Feb 16 09:17:57 2014 : Error: rlm_sql (sql): Error getting data from database Sun Feb 16 09:17:57 2014 : Error: [sql] SQL query error; rejecting user Sun Feb 16 09:18:00 2014 : Error: rlm_sql: The 'Attribute' field is empty or NULL, skipping the entire row. Sun Feb 16 09:18:00 2014 : Error: rlm_sql (sql): Error getting data from database Sun Feb 16 09:18:00 2014 : Error: [sql] SQL query error; rejecting user Do I have null attribute in my database ? or this null attribute is in request packet from NAS ? Best regards.