RTOS/cc2630: How to output the external signal RATGPO1 when sync is found in the receiver ?

Tool/software: TI-RTOS

Device : CC2630

Software: TIMAC,IEEE802.15.4 Medium Access control (MAC) software stack

Problem ： 

I can output the signal RATGPO0 to IOID2 by using the API as followed : 

MB_RFGPOCTRL_REG = RFC_DBELL_SYSGPOCTL_GPOCTL0_RATGPO0;
PINCC26XX_setMux(pinHandle, PIN_ID(IOID2),IOC_PORT_RFC_GPO0);

But, when I change the API as followed :

MB_RFGPOCTRL_REG = RFC_DBELL_SYSGPOCTL_GPOCTL0_RATGPO1;
PINCC26XX_setMux(pinHandle, PIN_ID(IOID2),IOC_PORT_RFC_GPO0);

Nothing happens on the IOID2 , so I kindly ask that how can i output the external signal RATGPO1 to IOID2 when sync is found in the receiver ?