On section 8 of this tutorial (our internet stuffed toy example) https://www.carriots...net_stuffed_toy
you can see how the listener should look like to make a tweet. This feature works fine. So the problem should be that if you copied and pasted the code, some extra characters might have been added without noticing. Please review that you don't have any line breaks.
Please also note that twitter API does not allow to tweet the same exact text twice in a row. Although a duplicate should be discarded and you should not get an 500 internal server error.
Anyway, if the error persist could you paste here the code of your listener?
BTW: You can also access the terminal console https://cpanel.carriots.com/terminal/
(or in the upper menu Debug&Log\console) and try your script before you put it in a listener.
Edited by mcastillo, 30 March 2013 - 09:54 PM.
I forgot to mention the console feature to try scripts