Can't resolve multiple constant drivers

I have a process type StateType is (ST_IDLE, ST_WAIT_DONE, ST_START_RX_DATA, ST_RX_DATA0, ST_RX_DATA, ST_RX_REG_COM, ST_RX_REG_ADDR, ST_RX_REG_DATA, ST_TX_REG_COM, ST_TX_REG_ADDR, ST_TX_R...