I tried putting a really long command in a command block and when i activated it it gave me a really long message. When i do it on single player everything works fine. Is it seriously impossible to put long commands in a command block on a server? Please help.
That depends totally of the support of your server or the server that you use... Ram and Memory... Also can be some restriction imposed on the server to not crash it. Change of server and look for another that supports your needs.