OK, it must definitely be "Bump" and not "gradient Bump". Gradient bump is for *.bum files. And you shouldn't use *bum files in Poser 5, which is what I think you are doing. Try this. Disconnect your bump texture from gradient bump, and plug your main texture into "Bump" and try different settings, starting from about 0.25 and try 1. If that works, make a new grayscale .jpg bump map from your main texture and plug that into "Bump"