I installed qtcreator 1.2.1 by downloaded it from the website.

qtdemo works. I can compile my program but the examples doesn't compile :

Qt Code: 
  1. Running build steps for project tabdialog...
  2. Starting: /usr/bin/qmake-qt4 /usr/lib/qt4/examples/dialogs/tabdialog/tabdialog.pro -spec /usr/share/qt4/mkspecs/linux-g++ -r CONFIG+=debug 
  3. Failure to open file: /usr/lib/qt4/examples/dialogs/tabdialog/Makefile
  4. Unable to generate makefile for: /usr/lib/qt4/examples/dialogs/tabdialog/tabdialog.pro
  5. Exited with code 5.
  6. Error while building project tabdialog
  7. When executing build step 'QMake'
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I install qt from ubuntu package... I tried with the package qt creator 1.0.0 it was the same.