Imovie "Peramerr:" when trying to prepare to make dvd

I'm trying to make an Idvd in Imovie using my 15" macbook pro.

It does not have a built in disk reader so I have a USB Superdrive.

Apart from not knowing wether or not the superdrive will record or write the dvd I also have the issue that

when I try to prepare it by clicking "share" then "Idvd" it starts to prepare for publishing but then comes up with "Peramerr: Error in user parameter list"

What can I do?