Look at the tail of your bullets.  Do you see a little copper cup, or do you see white stuff (like the top of a strike-anywhere match)?  Most pulls I've seen are missing the ignitors, which means they probably won't light.  Also, most of the time that a given lot of tracer ammo is surplussed, which these days means sold to a de-milling firm such as Talon, it's because the ammo had problems with "fail-to-trace."

Other folks have found that stick powders tend to light tracers better for whatever reason.

-Troy