Quote Originally Posted by Philip_Anselmo
QMAKESPEC has not been set, so configuration cannot be deduced.
There is another way to solve this. You have to set environment variable.
Start command prompt, write
set QMAKESPEC=win32-g++
For mingw. You have 2 do this everytime when start a command prompt.

In win xp. u can set a new enviroment variable by Contrl panel->system-> Advance -> environment variable.
here define a new variable. QMAKESPEC and set its value as win32-g++