Hey I hear ya, my two new Percs will not go near the BTA I have. They have decided they like one of my two huge mushrooms instead :-(
But, they might in time decide they like the BTA. They will pick what they prefer to host in.
They are such cute curious fish, I found that when I had just the one it would swim up and down the glass all day long, drove me nuts. I then got a mate for him and he quite that and they are together all the time swimming in and out of the mushrooms.
What size of tank do you have??