Text sent by Command Block is cut off when using your own Server

Hi! I downloaded the 1.5 Prerelease Server EXE and put my new map inside. I aktivated Command Blocks in the .properties File, set the default mode to Adventure and one commblock whispers new players a message when they push a Button. In Creative Mode when building the world offline (not running my own Server) the message was displayed properly (about 3-4 Lines of Text in one command block line). But when I run my own server and connect the text is cut off after 2 Lines.