I'm unsure why that error is being reported. It's not something we've seen before. It could be a character encoding issue or another URL inserted into the post or something like that. Here's what I'd recommend to try and diagnose things:
Please edit the /components/com_jfbconnect/provider/twitter/channel/stream.php file. At line 100, you'll see:
$status = substr($message, 0, 140 - $urlLength - 1) . " " . $link;
Change the 140 to a much smaller number, like 100 and test again to see if it works. If not, try a really small number like 50. At some point, if it works, post the full tweet that was made.
If it still doesn't work at 50, then we'll need to investigate more on-site. Could you please Private Message us admin and FTP credentials for your site so we can make minor modifications to the code to diagnose things further. You can PM us by clicking the mail icon under my name to the left.
Thanks,
Alex