Oracle Database Discussions

the error happened the production database.the case is that enough space, unlimited tablespace for the table owner,but the table index has another owner,the index has a tablespace,the error happened on the index which was in the tablespace. at that time,we were worried,because the error had affected the foregrounding,then we execuated "ALTER USER the table_owner QUOTA <integer> [K/M] ON <tablespacename>;" but now i make a test which reappeared the error,the error has reappeared,but i execuated ALTER USER the table_owner QUOTA <integer> [K/M] ON <tablespacename>; " the error still hanppened. so i don't know if i make a mistak to decide the production database error??? please tell me why ,thank you !