Programming Custom nRF52811 Boards based on Fanstel Module BM833AF

I have a Fanstel Evaluation board which can be programmed  through 52 DK board, no problem there and i also have built a custom board using the BM833AF modules based nRF52811,the issue i'm having is that few are booting up with factory default firmware but when i try connecting to DK board it does not get detected, i'm using SWDIO SWDCLK VDD and GND Pins and powering the board through the DK board itself, i'm using P19 header to connect, i'm made sure to connect GND detect to GND and VDD to VTG, if it was hardware issue the other boards would also been having the same problem, if it had something to do with assembly then the board itself would not boot up. 1 in 10 boards are having this kind of problem, any clues to what might be causing this would be very helpful.

Thank you and regards
Paul Canon