Material isn't displaying in Android? (Node DDX not supported)

This is the material that isn’t displaying correctly. When I launch for android the landscape (what the material is used for) has no material. If it matters I have Tangent Space Normals unchecked.

I get build warnings like: “LogMaterial:Warning: Failed to compile Material Instance /Game/Levels/cave.LandscapeMaterialInstanceConstant_159 with Base LowPolyMaterial for platform GLSL_ES2, Default Material will be used in game.”

“LogMaterial:Warning: (Node DDX) Node not supported in feature level ES2 LogMaterial:Warning: (Node DDY) Node not supported in feature level ES2”

Does this mean I can’t use node DDX and DDY for Android? Is there an alternative?