Structures broken?

Hello everyone, I've made a mod and I have a few custom blocks and they work. But I made a structure and saved it as a schematic and I made it into my mod to spawn in plains biomes. It's set to 100 buildings per 1k chunks but I cannot ever find one. I went up from there to 1k per 1k spawns which is 1 building per chunk but none spawn! I cant seem to get them to spawn in at all and im wondering if its how I did it or if its because I used my own mod blocks in this mod for the building... please help asap, thanks.