You probably just need to play around with your font and font size.

I use BC13 narrow at 3/8" high and it works great on a laser printer.

However, I had to experiment with that to get it working. Mine stops working if I make it larger. Either the string is too long or the bands are too wide?? You'd think larger would be better, but it's not.

Just make sure you test it with short and long strings.
like
*a*
*my long test string*