Is it installed on the server? If it isn't, then this happens for a reason. The server has no idea what you're trying to obtain, therefore it's basically like... You giving a 2 year old baby a computer and telling him to write a C++ program, then the baby puking onto your face, signaling for you to get out.
So, you have the client version installed on your client and it works correctly? And you installed it on the server correctly?
Yes I enjoyed playing around with the grappling hook in single player for a while, and SMP failed because i couldnt pick up crafted items. I would click them and i would crash. Since the mods are installed the same way i dont know why client would work but server would not.