That isn't a tackle action node the tackle take down itself is not usually functioning alone. I know they use an action node for the J_Damon but I am to lazy to look for the action node. This should do a run tackle attempt if you test it out.
PedSetActionNode(Damon, "/Global/J_Damon/Offense/SpecialStart/StartRun", "Act/Anim/J_Damon.act")
Wait(1000)
PedSetActionTree(Damon, "/Global/J_Damon", "Act/Anim/J_Damon.act")