Provide more information and troubleshooting help when Qt is deemed not to be installed correctly. Currently if you add a Qt version which Qt Creator determines to not have been installed correctly, it can be difficult for the user to know what is actually causing this (especially if it is generally working for them outside of Qt Creator). So it would be good to provide extra hints as to why Qt Creator failed to see it as properly installed.
This could be done in conjunction with the documentation to give extra troubleshooting tips in order to solve the cause of the problem. For example, it could be the qt.conf is bogus, or Qt needs to be reinstalled and thus in the latter case, knowing what to check to prevent it happening again would be good.