Secure DFU ble debug code


I am using sdk 15.3 example code of DFU (secure_boot loader \ pca10040_ble)

I want to debug code but i can not.I getting error like that "Error Flash Download Failed - Cortex-m4"

I am using s132_nrf52_6.1.1_softdevice .i have using nrf52832 board and Compiler Keil 5

Also i have setting address of IROM1 = 0x78000 and Size 0x6000,  IRAM1 =0x200057B8 and size 0xa848.

Please help me to resolve these query