Issue: When mental ray cannot locate files used in render appearances (including decals), it continues the rendering process, and it renders that part of the view as black. (Click Cancel if you want to cancel the rendering process instead of proceeding.) For example, if an image file that defines a custom color or texture is missing, elements to which that material is applied display as black in the rendered image. Likewise, if a decal image file is missing, the decal displays as black.
When you move the mouse over the Image File field for a decal, color, or bump pattern, Revit displays the path of the image file. Check whether the image file resides in the specified location. If not, check whether the image file resides in a path specified on the Rendering tab of the Options dialog. (See .) If the Revit project was sent to you by another team member, you may need to request the relevant image files.