DFU clock and custom made board

[Nomi]

I am using nrf51422 sdk v8.0 on pca10028 kit and softdevice s110. My DFU and custom made application works fine when i use clock SOFTDEVICE_HANDLER_APPSH_INIT(NRF_CLOCK_LFCLKSRC_XTAL_20_PPM, true). Then i transferred my codes to my custom made board but all codes work there when i change clock to SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_RC_250_PPM_TEMP_4000MS_CALIBRATION , NULL). But now i want to add DFU to my custom board. i changed the clock to SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_RC_250_PPM_TEMP_4000MS_CALIBRATION , NULL). in dfu_dual_bank_ble_s110_pca10028 an example project from keil packs. dfu advertise nicely but when i try to upload my application there comes an error "the connection has been lost". Can someone point the error is it because of clocks or something wrong in my code.?

[Nomi]

changing to the clock you gave pca10028 will not get out of dfu mode. i changed the clock as you told me in dfu_dual_bank_ble_s110_pca10028 example. Then starting pca10028 in dfu mode i uploaded hrs_s110_8_0_sdk_8_0.zip. But the hrs did not start the board is stuck in dfu mode it is not getting out of dfu. I tried uploading my custom application too but the board still remain stuck in dfu mode. How do i get it out of dfu and start advertising my custom application.?