What to do about this error message?

Thanks!

Rik Verhoeven

Dear sketchuppers,

For a client I have to model a ceiling with different sizes of wooden slats. They varies in thickness, width and length. Other fact is that the ceiling is a double curved surface.

So i thougt to model the ceiling and use a texture with a self-made displacement map.
But when I render the displacement doesn't look nice at all.

See attachment for what I mean.

Any suggestions?

Greets Rik Verhoeven