Till yesterday I was using Qt Creator 2.4.something and Qt 4.8.1 and since I noticed that there was a new version of MingW avaliable on its webpage, I decided to install it. But the problem is that after trying to do it unsuccessfully, I decided to go back to the original point and continue to work my projects whitout loosing anymore of my time ^^

Then I went o the Qt SDK project manager and after deleting mingw folder in QtSDK's directory, I downloaded MingW 4.4 once again. After that, I noticed that despite being able to run my software, I'm unable to do the action "clean all" and therefore "Rebuild all", with Qt Creator giving me this message:

:-1: error: Qt Creator needs a tool chain set up to build. Configure a tool chain in Project mode.
The problem is that I do have a tool chain configured in my Project session:


So I simply don't understand what's actually wrong :x

Thanks for any advice,