Landscape Layer paints black

I just added a LandscapeGrassType to my landscape and for some reason when I paint the layer, the grass paints but the material goes black. I’ve never had this issues before. Any ideas?

Screen Shot 2016-04-04 at 5.04.13 PM copy.jpg

Had this a few times before, try painting over the whole landscape with the default layer and then painting with the other layers again - that worked for me.

Thanks, I’ll try that!