C++ – Run button is disabled in Qt Creator

This happens even on a freshly created, empty project.

The Run (and also Debug) buttons are disabled for the Qt5 configuration (they're enabled for the Qt4 configuration). The build button is not disabled, however, and it works – I can build the project, but I can't run it from Qt Creator.

They are disabled in the Build menu as well. Everything is enabled and works fine for the Qt4 configuration, however.

It's a Qt/C++ project, on Windows 7 (32-bit).

Edit:

I found a couple of related questions – RUN button no enable in QtCreator for QML project and http://qt-project.org/forums/viewthread/15737, but they have slightly different circumstances, and they don't show a clear solution. I'm posting them in case they help, though.

Edit 2:

I checked the run configuration for Qt5, as suggested by @Blueman and @Fabian, and the executable field is empty (and also disabled), even though the Build configuration correctly specifies the path. Moreover, I get this error – "The .pro file untitled2.pro could not be parsed." Here's a screenshot: