TNT Cannons won't work on Bukkit Server?

Ok, so I tried making a TNT cannon -yes I am 14 and I still play minecraft- on my bukkit server and used the same exact design as when I tested it on my survival server. However, it didn't work on my server (it did work in survival). I have no plugins on my bukkit server right now. I used a similar cannon to this one with a few adjustments to make it better. On the server, when i light the tnt that should launch the other one, rather than staying in the water, it glitches (probably) and jumps on top of the TNT cannon where it explodes, blowing up the cannon, any ideas on how to fix this?

Read more: TNT Cannons won't work on Bukkit Server?