I assume you have set the appropriate rights for users and groups. As well as the links and mountpoints for the drive,

After reading your post, and as I got that O/S just a few days ago, and do not have everything settled yet, I tried to record a DVD using K3b aas you did.
First I'd a prob with users and groups and needed to log as root. Tried a simulation and it did fail, Then I decided to burn a direct copy I needed and it went through.
But, at the end K3b couldn't see the discs content, besides I could do it from the reader.
Went to the Sys Configuration and added links and mountpoints for all my drives.

Switched to win2000 and could see the disc's content using 2 dif drives.

Went back to Suse and all drives were now mapped with the right icons but for one, besides it worked when I did introduce a DVD-RAM.
Afterwards I could read the copy content in all drives.
By the way, I used Memorex DVD-R to make the copy and a NEC 4551.

Did you configure K3b or change the default one? Did you make a simulation? It can give you an indication about what can be wrong with your sys. If it fails and you read the logs.