bAtari BASIC Game not working?

[fultonbot]

I have really simple bAtari game I'm trying to get working on the Harmony cart.
It just displays a black screen.
It does nothing fancy. Here are the kernel options:
 

set tv ntsc

 set romsize 4k

 set kernel_options player1colors readpaddle no_blank_lines

 

Is this any kind of known issue, or is it more complicated than that?

Thanks,

Steve