Difference between two Qt4.8.6

[Crashz83]

Hi,

I am currently developing an application to handle TouchEvent. I use the example code Qt attached:
http://doc.qt.io/qt-4.8/qt-touch-pinchzoom-example.html

I have got a multi-touch screen and i'm working on Ubuntu 14.04 LTS, with Qt4.8.6.

I have a problem with my program... When I compile my program with the Qt system (Qt4.8.6), the pinch zoom operates correctly.
However, when I use the Qt I installed (Qt4.8.6), touch events are not caught...

Here are the versions that I use of qmake:
qmake.jpg

Finally, here are the libraries that my program uses after compilation.
With Qt4.8.6 distribution:
QtOS.jpg

And Qt4.8.6 I installed:
QtTrolltech.jpg

I tried several times to install Qt with different compiler options, without success.
If someone has an idea...

Thank you in advance!