export QTDIR=/home/user/qtsdk-2010.05/
export PATH=$QTDIR/bin:$QTDIR/qt/bin:$PATH
export LD_LIBRARY_PATH=/home/user/qtsdk-2010.05/lib/:/home/user/qtsdk-2010.05/qt/lib/:$LD_LIBRARY_PATH
please change qtsdk-2010.05 to your sdk path
and make sure the binary path and lib is correct, then qmake ,make clean , make