Can't use height blending alongside texture bombing?

I tried to make a material that height blends two material functions which are just a basic material with some texture bombing applied to them. But I get an error that I’m using a DDY node or something?

Anyways, I have 0 clue what i’m talking about, so here is the link to the materials and the material fumnctions. I didn’t include the textures since I didn’t want to share a huge file, but I guess you can use any texture just to test it out.…ew?usp=sharing