Can't add a qt class to my project

[MaramWadi]

Hi ,
I am trying to add a qtClass using class wizard , I had chosen Qt4GuiClass then press next , then a message display to me says "it is impossible to add a qtgui class to the current project, as it was not created using Qt4VSAddin"

so why this message displayed to me and how I can add a qt class to my project??

note: I use VS2010