A number of us had problems with images we wanted to use for diffuse maps in sansar. We found that we could not get these textures to render in sansar, and that when the objects were uploaded to sansar they appeared to be blank.
We have discovered that textures need to be powers of 2 in order to display reliably in sansar, i.e. 1024x1024, 256x512, etc. So, make sure that you open your textures in photoshop or gimp or whatever graphic program you are using, then resize them in powers of 2 and save them as png files, before using them in sansar.
At this time, not sure if this is a problem only with blender. Perhaps people can check this in maya and other programs.