Mp3 Patch Encoder downloaded, but how do I use it?

I have Cubase Le5 and I just liscenced and validated the MP3 Patch Encoder. When I open my songs and go to export, mp3 is not listened on the drop down for file format in the audio mixdown. Everything is validated though. And I paid money for it so its kind of annoying to not be able to use it. Please help, thanks. :smiley: