The debugger only works when in development mode.
All other modes (acceptance, test or production) disable the debugger module.
Is the breakpoint enabled? (that is, is the circle fill red, it is white if it is disabled). That should be enough to trigger it if the activity is triggered. (and note that the popup might popup behind your other applications, so try to minimize every other by hand)
And did you redeployed after setting the breakpoints?