This message is generated when the second argument in SurfaceGraphics is not an array or is not compatible with the array given in the first argument.
The first argument in SurfaceGraphics gives an array of height values, and the second argument gives an array specifying how the surface should be shaded.
If the array of height values has dimensions n1 by n2, the shading array is expected to have dimensions n1-1 by n2-1.
Off[message] switches off the message; On[message] switches it on. For example: Off[SurfaceGraphics::shade].