After I put a new selfcreated meterial into the landscape material the landscape turned black , what could I do to fix this?

After I put a new selfcreated meterial into the landscape material the landscape turned black , what could I do to fix this? . I made a normal material out of three layers and the material is like grass green. I made sure that the lightning is good to and normaly the materials shouldn t be the problem too. Thx for help