no errors.
It just doesn't open up the Maxwell render app.
Even if Maxwell is running in the background. When I press the render button in Maya... nothing happens.
I have the Render engine set to Maxwell in the settings.
Try running Maxwell manually from the Application folder once. The first time it's started it registers itself with files with the MXS extension, and that's how the Maya plug-in knows where Maxwell is located, to be able to start it when you press render. This is covered in the FAQ, second question: http://support.nextlimit.com/display/knfaq/Maya.
FOUND IT !
My Painter App was set to open my MXM files. In Mac OS I had to select one of my MXM files and chose "get info" and found the "open with" option. I set the app to Maxwell and then hit the "Change All" button.
Now it works! And all my file icons look correct.
Ao, in case someone else is having this issue, you will know how to fix it.