First, report back with what is actually inside your file... and more information in questions below
Codec & Format information, read both links in reply #1 http://forums.adobe.com/thread/1270588
Report back with the codec details of your file, use the programs below... A screen shot works well to SHOW people what you are doing
http://forums.adobe.com/thread/592070?tstart=30 for screen shot instructions
Free programs to get file information for PC/Mac http://mediaarea.net/en/MediaInfo/Download
And, the more information that is needed
From the Premiere Elements Information FAQ http://forums.adobe.com/thread/1042180
•What version of Premiere Elements? Include the minor version number (e.g., Premiere Elements 9 with the 9.0.1 update).
•What operating system? This should include specific minor version numbers, like "Mac OSX v10.6.8"---not just "Mac".
•Have you installed any recent program or OS updates? (If not, you should. They fix a lot of problems.)
•What kind(s) of image file(s)? When talking about camera raw files, include the model of camera.
•If you are getting error message(s), what is the full text of the error message(s)?
•What were you doing when the problem occurred?
•What other software are you running?
•Tell us about your computer hardware. How much RAM is installed? How much free space is on your system (C:) drive?
•Has this ever worked before? If so, do you recall any changes you made to Premiere Elements, such as adding Plug-ins, brushes, etc.? Did you make any changes to your system, such as updating hardware, printers or drivers; or installing/uninstalling any programs?
And some other questions...
•What are you editing, and does your video have a red line over it BEFORE you do any work?
•Have you viewed the tutorial links at http://forums.adobe.com/thread/1275830 page?
•Which version of Quicktime do you have installed?
Answers are in the details, and unfortunately you have not supplied us with enough to help us help you.
First, what version of Premiere Elements are you using and on what computer operating system is it running?
What are the properties of this "MPEG-4 movie" that cannot be imported into some version of Premiere Elements?
Interlaced or Progressive
Pixel Aspect Ratio
Properties readout programs such as MediaInfo and gspot would give us this type of information. Sometimes we can learn
enough about the video from just knowing the brand/model/settings of the camera that recorded the video.
And, when the video cannot be imported, are you getting an error message? If so, what is it stating?
We can get into the specifics of the project and the computer environment, once we get the basic information.
Please review. We will be watching for your answers to the questions.
If questions or need clarification on anything written, please do not hesitate to ask.