Hi ,
Check to see if you have the texture T_Pebble_D in your UT project. you have to migrate the textures and normal maps for the material as well as the material itself. T_Pebble_D is in the vehicle example. If you did migrate the pebble texture over it is probably not in the same general filepath that the original material was looking for. In that case you simply have to find the texture and reapply it inside of the material editor. That should solve the problem.