Are you using the project preset for this camcorder?
Also, how did you get the video from your camcorder into your computer? Did you Premiere Elements to download it?
I took the video to my computer via SDHC card. JVC has a very generic editing program, and the audio/video works fine in that program. The audio however will not work in Premiere. What is the "project preset"? Is that a setting in Adobe Premiere?
Use the free http://www.headbands.com/gspot/ to find out what is inside the video file
You then tell PreEl to use project settings to match the video file
The program user guide is available as PDF on the install disc... find it and read it
You really need to define what you are recording with that JVC camcorder and trying to edit in Premiere Elements 4. Are you recording AVCHD (represented as MPEG4 AVC/H.264) and frame size 1920 x 1080 30 frames per second OR 1440 x 1080 30 frames per second OR what might be AVCHD Lite (MPEG4 AVC/H.264) but with the lesser resolution of 1280 x 720, 30 frames per second?
AVCHD is not supported by Premiere Elements 4. AVCHD support for Premiere Elements exists for versions 7 and 8. There is a special case where, with certain Sony Vaio and Sony Add On, you end up with AVCHD support for your setup. As I recall, in the days of Premiere Elements 4 users who did not have this special Sony Vaio, they needed to convert the AVCHD to a non AVCHD format in order to work with it in Premiere Elements 4.0 (with 3rd party software).
To avoid the speculation, best to download and install the first utility named gspot and give us a read out for Video Codec: Name: Status; Audio Codec: Name: Status; frame rate, frame size, etc. Be sure to indicate what the file extension is for these videos (.mov, .mp4, .m2t, .mts, .m2ts, or other.
From what I have read this camcorder does not record SD, but is probably recording AVCHD and HDV. If I am on the right track with this one, have you taken time to look at Premiere Elements 4 with other JVC formats, like HDV, besides whatever you are using now?
I would also recommend against using the program that came with the camcorder to capture your footage and then using Premiere Elements to edit the footage. It's quite possible the JVC software is changing the footage into a format that it can work with but Premiere Element can not.
Have a look at my free Steve's Tips article "Project Presets in Premiere Elements", available at Muvipix.com.
It explains which preset you should be using for this camcorder and how to set it up.
JVC camcorders do tend to have some unique problems because of the way they create and save their video files. But the Hard Drive, Flash Drive Camcorder presets are designed specifically to interface with JVC-G camcorders.
As the article says and as I indicate in my books, selecting the right project preset is ESSENTIAL to creating a successful video project.