Hi, I am building a factions server but when I try to make a tnt cannon, the first cannon wont push the one infront of it...! Please help

These are my plugins: worldedit, mckits,essentials,groupmanager,per world plugins,clearlag,alpha chest,survivalgames,votifier,banhammer,multiverse-core,protocolib,worldguard,mcore,punishmental,multiverse-inventories, essentialschat,mcmmo,multiverse-portals,anticobatlog,vault,essentialsspawn,hubessentials,enjinminecraftplugin,dynmap,spawnergui,chestshop,factions,craftbay,value,obsidiandestroyer