Need Help on Installing qwt on qt 5.0.2

Hey all, I am a noob in this forum, but i was using QT since 2 years ago, i used to create robotics project using qtserialport and opencv. I usually used qt SDk 1.2 and yesterday my professor told me to upgrade to qt 5.0.2, and so i did. He also told us to install qwt to be used on his signal and system excercises. I used windows 7 32 bit, and i completely uninstal qtsdk and remove the path, install qt 5.0.2, which i download from http://qt-project.org/downloads, and then adding the path to my system environment as usual, and then try running examples on qtcreator, and all works fine, the problem came when i tried to install qwt, i extract the zip and running qt command prompt, directed it to the extracted folder, and run qmake, it said cannot read mkspecs, i never found this problem before when i try to install library, i already tried a search but i got nothing on the web, here is the screenshot :
Attachment 8932
as uwe said nothing could go wrong on running qmake, mingw32-make, and mingw32-make install, i used to use this command in building libraries and this is the first time i met this problem. Please somebody enlighten me for this problem...

Obviously your Qt installation is broken.

Uwe

Ok, i solved this problem, all i do is call qmake -unset QMAKEFEATURES, and everything went smooth.. The qt installation is fine, because i can run the examples from qt.. Thx a lot by the way