If you have clear water, crappie will not go into that light but work around the edges. On Possum Kingdom Lake, mercury or LED lights just above the water work better for crappie. The green LED or halogen lights are good for sand bass and stripers but crappie are not keen to be illuminated int that light. Considering some of the huge fish going through those lights I don't blame them. Any Crappie wise enought to live to be 10 inches knows better than be illuminated in that green circle.
Lavon may be a different deal since the water is stained. You could pick up a solar LED garden light and try that as well as that submersible LED. It's also been my experience that these lights work better in summer when there are lots of ghost minnows and small shad that can be attracted to the lights.
John 21:3 Simon Peter saith unto them, I go a fishing. They say unto him, We also go with thee.