ambiguous recipe error adding compressor recipe

I am trying to add a compressor recipe that uses 1 obsidian Plate as the input.

"ic2.api.recipe.Recipes.compressor.addRecipe(new ic2.api.recipe.RecipeInputItemStack(ic2ObsidianPlate, 1), null, new ItemStack(sT_Items.itemCasingObsidian, 2));"

And this is the error
java.lang.RuntimeException: ambiguous recipe: [1xic2.itemPlates@7 -> [2xitem.itemCasingObsidian@0]], conflicts with [[1xic2.itemPlates@7] -> [1xic2.itemDensePlates@7]]

From what I know and can find, there is no recipe that takes 1 obsidian plate to make 1 dense obsidian plate.

Quote from Blockmaster139

It looks like the problem here is that you are trying to add 2 different recips with the same input. I would suggest making your obsidian item casing crafted with the metal former instead.

Bah your right! I completely forgot that was a thing ...