flashtt

I'm creating a resoucepack with models , like stairs. When in vanilla Minecraft, it works well. when Minecraft 1.12 with only forge mod ( version 1.12-14.21.1.2415 ) I try some Minecraft versions (1.8.9/1.9.4/1.10/1.11/1.12)，same results. only when I used 1.8.8 with forge （1.8.8-11.15.0.1594, a beta version）,display normally. How can i solve the problem ? PS: not good at in Englsh, sorry.