Placed TNT won't ignite on my plot.

[ConnorWithoutAnE]

I'm making a bow spleef game where the floor is made of TNT and you use a Bow with Flame to ignite the TNT but for some reason the already placed TNT never lights. Is there some way to allow the TNT to ignite or to replace the TNT block with Primed TNT?

 

[ARMcPro]

DiamondFire does that for security measures, you can fix it by doing this:
On Player Event: Projectile Hit -> check If Event Block Equals: TNT, if it is, Set the Block at the Event Block Location (to remove the old tnt), and summon a Primed TNT at the event block location

the event block location is a Game Value