Small mistake in what XxLMM13xX told you to do
calling_ply is a player and can't be printed into the chat, what you want is to grab the name of the player
ULib.tsay( calling_ply, calling_ply:Name().." Said: "..message )
I also changed the _ to calling_ply since _ is not the player variable
You could also use calling_ply:Nick() since Name() and Nick() do the exact same thing