How to change PANID and channel

Hi, 

For CC2538, how can I change the default PANID and channel setting.

I am using 

"

uint32 MyChannel=0x80000;

uint8 status;

status=osal_nv_write(ZCD_NV_CHANLIST, 0, sizeof(MyChannel) , &MyChannel);

uint16  myPANID = 0xF78A;

status=osal_nv_write(ZCD_NV_PANID, 0, sizeof( myPANID ), &myPANID );

"

But both status return "10", i.e. NV_OPER_FAILED. I have called osal_nv_init before calling write function. 

One more question about this "osal_nv_item_len( ZCD_NV_CHANLIST )", it is always 0. 

Thanks.