gdb.exe crash when into breakpoint

I’m using Qt Creator 3.5.1 with qt5.5.1
I created a console application, set a breakpoint. it works.

When i set a breakpoint in a QT Widget Application, the breakpoint is not hit.

I moved the breakpoint to a button clicked function. start debuging , push the button. GDB no responding.it hang.

it’s builded in Debug mode.

I don’t know why