app is running,but jlink can not connect board

[fifn]

It is bad yet?but i changed Another ic(nrf51822 GFAA G3),it can be connect,so What's going on,then the new ic also jlink can not connect board

[Asbjørn]

You have a custom made circuit board with a nRF51822 on it. The application is running, but you can't get Segger j-link to find it? How are you powering the nRF51822? The Segger J-link lite needs the VDD of the nRF51822 to be close to 3.3 V when programming.