I tested here once again at it works as it should. Remember that, to use
/teller <word>, you must be in a channel or query window, or else it wont work.
You can use it in 2 ways:
/teller word to send the sentence to the channel/query - or -
$teller(word) to return the sentence (in a script, maybe). Also make sure you copied the whole code.
Good luck
Zyzzyx.