What are you trying to import?
You may import VOB files from a "movie" DVD to edit in Premiere Elements... anything else you need to provide details
Directly editing a VOB... or Ripping a VOB to edit using a note from Jim Simon -http://forums.adobe.com/thread/1322647
What computer operating system is your Premiere Elements 11 running on?
If you are trying to rip VOB (video files) from the DVD-VIDEO format on a DVD disc, you do not need to convert them into any other format.
You simply insert the DVD disc in the DVD burner tray.
Manually set the project preset to DV Standard or DVD Standard Widescreen, depending on how the DVD-VIDEO on DVD disc was produced.
Detail for manual setting of project preset is described in that blog post.
Then you use Add Media/"DVD Camera or Computer Drive"/Video Importer to bring your video files (VOBs with a file name such as VTS_01_1.VOB and so on into the project and Timeline.
Are you doing all that? Please clarify. We can supply more details as indicated.