IWR6843ISK: How to configure SOP2 pin as a regular GPIO output ?

Hello experts,

After iwr6843 boot up ,i try to configure sop2 pin as GPIO output ,however it seem doesn't work ,pin level remains low.

can you tell me why ?

here is the code :

    Pinmux_Set_OverrideCtrl(SOC_XWR68XX_PINP9_PADBA, PINMUX_OUTEN_RETAIN_HW_CTRL, PINMUX_INPEN_RETAIN_HW_CTRL);
    Pinmux_Set_FuncSel(SOC_XWR68XX_PINP9_PADBA,SOC_XWR68XX_PINP9_PADBA_GPIO_27);


    GPIO_setConfig (SOC_XWR68XX_PINP9_PADBA_GPIO_27, GPIO_CFG_OUTPUT);
    GPIO_write(SOC_XWR68XX_PINP9_PADBA_GPIO_27, 1);

Thanks ,

Simon