Games : Terraria Truffle Problems

I often surf the terraria wiki to look for more interesting things to do or make. So when I found out about the truffle it (the last NPC I need) it sounded like a great thing to get. The truffle had been moaning at me for AGES now (named muscaria) even though I didn't know of its existence. Now I have made a surface mushroom biome and filled all the boxes; but alas, still no joy. What am I doing wrong?