nRF52840 Dongle Write problem

Hi,

I tested NRF52840. but, I can't download it.

I use the file in \ nRF5_SDK_15.0.0_a53641a \ examples \ ble_peripheral \ ble_app_blinky \ble_app_blinky_pca10059_s140.hex, but the write button is not active.

Is this a bug in nRF connect?
or I create a new hex file?
Thanks.