Frobenius

So i'm learning how to mod bfme I and i'm trying to figure out how to respawn cave troll lairs or goblin lairs.

What i got so far is I made a child object of a IsengardDeployedExplosiveMine with model GPMonument2, that spawns when a cave troll lair is destroyed. The child object has a lifetime of 300000 miliseconds and when it expires it creates a cave troll lair. 

So far so good, but the created cave troll lair cannot be attacked by melee units, for example rohirrim hordes or gondor knights, it can only be attacked by ranged units.

Does anyone know why this could be and be willing to help me out.

Or if anyone has an idea to keep trolls and goblins in game after their lairs have been destroyed it would be appreciated also.

Thanks,