So, try rename it in the Outline by removing the .PNG and export to POV-Ray again.
Also, what's the Wings3d version you are using?
Because that error was reported before, I believe you are using the 1.5.2 and there is a fix for that in this thread: [1.5.2] Pov-ray export bug
Also, what's the Wings3d version you are using?
Because that error was reported before, I believe you are using the 1.5.2 and there is a fix for that in this thread: [1.5.2] Pov-ray export bug