Error: Modo could not be launched and perform the conversion

I'm using Unity 4.2, and Modo 701 on Windows 7, and Unity 4.2 and Modo 701 on Mac Mountain Lion.

In Windows 7, when I create a scene in Modo, and export or save to the Assets folder of my Unity project, I get the following message when clicking on the scene in the assets folder:

"Modo could not be launched and perform the conversion"

Consequently, the mesh or scene is not draggable to the Project window.

This does not happen with the same exact scene but on the Mac.

Any suggestions?

This question is nine years old, but I am still suffering from this problem.