Unable to erase or write Flash memory in CC2531

I am trying to erase & write on flash memory in CC2531. Although i am able to do it successfully till memory 0X0000 to 0X7FFF in the CODE memory but i am unable to do the same in CODE memory from 0X8000 to 0XFFFF. Trying to find out the cause i tried setting the Bank memory as start from 0XF000 to 0XFFFF in the Bank Start under Project/Options/General Options/Code Bank Tab . Then i am able to write & erase the memory till 0XF000. But still not able to access the full 64Kb memory as was represented in CC2531 Datasheet. Please help me out from this problem I have also tried mapping XDATA Memory into CODE memory but with no help. Also tried to access it using pragma #pragma location={address|NAME} but still it is also not of any use.