In addition, the simple material room does not distinguish between a diffuse/albedo map and greyscale/normal/transparency maps, so you still need to set the gamma values in the texture manager panel.  The Texture Manager window can be opened by left clicking on the image map and selecting 'Use Gamma value from render settings' for Diffuse or 'Custom Gamma value' = 1 for all other maps.  Also, the percentage amount of each map needs to be manually dialed in to activate the channel; the only exception is the Normal map which already has its value set to 100%