Kinnect Gesture Detection

Hi ,
I am new to the Kinnect Development. I have compiled the Skeleton detection example and that is working fine. I am getting left hand and right hand gestures properly detected. When I am trying to use the same flow of code for Thumb Gestures (JointType_ThumbRight , JointType_ThumbLeft) I am not getting expected results. What I assume is it should detect the Right and Left Thumb . If that is not the case then how thumb joint detection works?

TrackingState thumbState;

					 body->get_LeanTrackingState(&thumbState);

					 HRESULT hrTest = body->GetJoints(_countof(joints), joints);

if (SUCCEEDED(hrTest))
					{
						ss.str("");

						ss << 0;
						ss << ".";

						if (thumbState == JointType_ThumbRight)
						{
							ss << 1;
						}
						else if (thumbState == JointType_ThumbLeft)
						{
							ss << 0;
						}

						m_GestureHandler->HandleGesture(ss.str());
					}

where did you find that example?

I got this example from GITHUB @cyrstem