Difficulty adding cloud from OpenNiGrabber in a Qt Ui applicaiton

Hi,
I'm doing a simple Ui application project in Qt, with a cloud object taken from an OpenNIGrabber. For some reason i'm having difficulty updating the cloud inside the QVTKWidget created in the UI.
I'm following the sample code in trunk called "openni_passthrough", and the code works fine, so the problem in the application that i'm trying to set up, it's my implementation. Hope someone have a look and see what i am doing wrong.
When i try to run the application, it opens the ui for a brief moment with a pcl::PointXYZRGBA cloud in it, but not a second passed and the application unexpectedly closes.

here's my main.cpp - http://pastebin.com/d3L7z2fh

grabber.cpp - http://pastebin.com/NM4jPs7q

grabber.h - http://pastebin.com/52gU2s1P

grabber.ui - http://pastebin.com/aVjDthyx

and my test.pro file - http://pastebin.com/CmaQgvsy

the main problem is on grabber.cpp.
Thanks in advance.

You must draw point cloud into viewer by envent timer of QT , and use QLocker to lock thread get data callback or otherwise.