使用VSCode调试Golang时如何在运行时添加断点？

After activating a debug session, the program started running. At this time, I tried to create a breakpoint. Unfortunately, it said "Unverified Breakpoint" and the color turned into dark black, different from the other pre-defined one (which was red). You can see more clearly on the image below. The debugger would never stop at the line of the breakpoint.

Did I miss any steps?