I do not know how long you have had your BTA, but my percs just started hosting in my LTA and the LTA has been in my 20G Hex for a week now. The process was gradual with them swimming closer and closer to it till wham, they decided to dive in, lol. I was really happy to see them hosting.
In my 40G display tank, my Clarkiis took to my GBTA within the first day. My GBTA is the size of a large pancake, whereas my LTA is much smaller, for now anyway.