File won't open by double-clicking
My program, called Graph.exe, saves files as, for example, MyGraph.gph, but double-clicking on MyGraph.gph does not run Graph.exe. Nothing happens, even though 'Open With' shows Graph as the associated application. The program is written with Visual Studio 2012, C++ MFC, on a Windows 8.1 PC. Running it as administrator makes no difference.
Programs written with Visual C++ 6 on Windows 98 or XP PCs run perfectly on Windows 8.1.
Ivor Horton's Beginning Visual C++ 2012 says nothing about this, in contrast to his Beginning Visual C++ 5.