I think you are trying to create a gradient color pattern. If so, you need to set the first color and the last one.
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[edited]
From that other thread
We set each color key and use Interpolate between them to create the gradient:
![[Image: palette_zpswso5yjlb.png]](http://i1330.photobucket.com/albums/w578/Micheus/Wings3D%20-%20Forum%20II/palette_zpswso5yjlb.png)
Calling Interpolate after the last color key (red) will result in that message you has pointed.
_______
[edited]
From that other thread
We set each color key and use Interpolate between them to create the gradient:
![[Image: palette_zpswso5yjlb.png]](http://i1330.photobucket.com/albums/w578/Micheus/Wings3D%20-%20Forum%20II/palette_zpswso5yjlb.png)
Calling Interpolate after the last color key (red) will result in that message you has pointed.