the poser preview of a texture is a low resolution sampling .. it looks very little like the final render. If you are in POser4, check to make sure the texture strength is set to 100. if it is set to 0, it appears in the preview at full strngth but does not render. In poser 5 you will need to check the same setting now called 'Diffuse Value' and make sure that it is set to 100 this is a more likely problem .. I do it myself occaisionally