SceneLoaderExcep: Failed to load texture '/filepath/file.png': PNG had 2 channels, only 1, 3 or 4 channels supported.

Indigo now supports PNG files with 2 components.
Please install a recent Indigo version such as 3.6.11: http://www.indigorenderer.com/forum/viewtopic.php?f=1&t=12309