Sometimes when camera angles are too shallow a photo texture will not be generated because of the large amount of perspective distortion. However when a project is done with only one photo and/or you have no better photos to extract a photo texture, there is an advanced materials setting which you can adjust to force the texture to appear.
Open the Materials dialog (from the Edit menu, or from the toolbar), select the photo textured material, then click ‘Advanced Material Properties’ button. Increase the surface normal angle threshold (i.e. the “is more than _ degrees from photo direction, do not use” setting).
This will force PhotoModeler to use the photo even if the angle between camera and surface normal is very large and the texture is distorted.