I just got this working.
I had to edit the plugin to do it though, so I am not sure if it will be a good long-term fix.
What I did was to edit the following linke
Code:
$vbulletin->templatecache['SHOWTHREAD'] = str_replace('<!--RTT-->', $vboptions[rtt_text], $vbulletin->templatecache['SHOWTHREAD']);
I changed $vboptions[rtt_text] to $vbulletin->options['rtt_text'] . Now it is working fine.