RTOS/CC2640R2F: Is it possible that enable/disable the watchdog multiple times?

Tool/software: TI-RTOS

Hello,

I use simplelink_cc2640r2_sdk_1_35_00_33.

In order to prevent the watchdog counting during advertising(refer to this post),

I want to disable the watchdog when my system sleeps and enable the watchdog when my system wakes up by IO interrupt or BLE connection.

I use Watchdog_open() and Watchdog_close() to enable and disable the watchdog, and I call this API in SimpleBLEPeripheral_taskFxn's infinite loop.

But I get a NULL return when the second times calling Watchdog_open().

How can I fix it?

Thanks.