Nero-import and edit vob,no sound

I have Nero 6.3 OEM. Using Nero Vision Express, I see the menu option
Make DVD…DVD Video, which I think indicates the DVD video Plugin
has been detected.
I continue to import my vob files from my dvd. While analyzing/importing,
Nero shows me a dialog box that says someting about Dolby and needing
to upgrade to Ultra or buy the plugin.
When I continue, my files are in, I can edit, the video looks great,
but there is no sound in the preview or when I burn my project.
So, I like the user interface, I am happy to buy the plug-in or upgrade
to Ultra, but I just need someone to tell me that doing so will work for me.

Update/Question:
After reading many posts, I think I will try buying the DVD Video Plugin for
$24.95. However, I think this just is a serial number I recieve via email.
I don’t see anyplace in Nero where I can enter a serial number to unlock the plugin. Can someone confirm by telling me what I will do with this serial number? (I say this because some posts have said the OEM comes with the plugin enabled and does not need a serial number, which confuses me.)

Since there appears to be no information on the Nero site about OEM versions, I suppose the included documentation you received did not mention this either? I don’t really know what you need to get your sound to work. Have you checked to see if there are any options beside Dolby? But it is funny you should mention that, because I seem to get a message like that and I am using Nero 7 Ultra.

The only plug-in I have used, basically presented a screen when first run to allow for registration.

Make sure and go through what other features you might like in the Ultra version. It might be better to check now to see if you would rather upgrade to the full version versus one plug-in.