What kind of situation the RS-CAN Lite of RL78/F1x can't be changed mode ?

I can't change the CAN mode from reset mode to Channel Communication Mode ?

1. Set C0CTRL = 0x00 to make RS-CAN enter Communication Mode

2. Read C0STSL to check the the mode, and always get value C0STSL = 0x01

Why i can't change the mode ?