Because ^x03 is the color of the index (player), which is the first argument of the function. When you send the message to all players at once, you use the index "0" and the plugin is trying to get the team for player "0", which is invalid. When you use "id", instead of "0", there's no problem because it gets the team from "id". You should send the message to every player sepparately, by using "id" or fix the .inc file.