QTouchEvent fail to work for wacom cintiq hd touch

I experienced mtdev and Linux Multi-touch (MT) Protocol B, and I found that qevdevtouch also open the device file descriptor, then processInputEvent for ABS_MT_xxx https://qt.gitorious.org/qt/qtbase/source/1fa3627423a73fe19333e2e016feb35cdf8cd1ea:src/platformsupport/input/evdevtouch/qevdevtouch.cpp#L228

But QTouchEvent fail to work for wacom cintiq hd touch (the price is $2499!) product http://www.wacom.com/en/us/creative/cintiq-22-hd-touch

It is strange that my testcase is able to work, for example sudo ./read_mtdev /dev/input/event16, when I use 2 fingers to pinch, it generated (XTestFakeKeyEvent) CTRL+/- to X11 Window https://github.com/openiSOFT/Kernel-Document-zh_CN/blob/master/input/touchpad_demo/read_mtdev.cpp

But QTouchEvent is able to work for egalax projected touch screen http://www.eeti.com.tw/PCAP.html and ACER`s synaptics (touch pad)

QDeviceDiscovery`s fault?