I can't see that you're doing anything wrong.
Some fish are just too 'spooky' to feel comfortable in lower level tanks.
I am interested in suggestions on how to get my A. luelingi to spawn. They are in a 10G tank with 6 bloodfin tetras and 3 serpae tetras. I've had and will hide at almost any sudden occurence. I currently feed just the frozen foods. Any help is appreciated.