What program did you use to get the video from the camcorder into the computer? You can not capture with a different program, in your case, and then edit in Premiere Elements.
1) Ensure that your Premiere Elements project is using project settings for a widescreen DVD/Hard Drive Camcorder;
2) Finalize the DVD in your camcorder and then place the DVD disc in your computer's DVD drive; and
3) Use Premiere Elements' Media Downloader to capture your video (Get Media, from DVD)
The first thing that I would do is use Interpret Footage and tell it to accept the footage as 16:9. There are flags in the files' headers that indicate the Aspect Ratio. Different cameras also shoot Widescreen differently too. With some footage, PrE cannot read those flags properly (though with most material, it does just fine), so Interpret Footage will usually help PrE do what it cannot do by itself.
Hope that this helps. Also, can you give us info on exactly how your camera achieves 16:9? As stated above, different cameras handle it differently. Some shoot true 16:9, while some use anamorphic to squeeze the footage into 4:3 and then tell the editing program to un-squeeze it later. Others just crop 4:3 to make it look like 16:9, when it really is not. If your camera's manual does not go into enough detail, and many do not, you can download the great, free utility, G-Spot and run one of the files through it to find all of the specs. on those files, including the Aspect Ratio and the PAR (Pixel Aspect Ratio).