Which Share destination did you select?
Under Disc there is a preset for MP4 to BluRay disc.
Otherwise, you can set up an output manually for iPod to meet your specs.
Note, however, that the program is not editing your MP4s natively, so the file you output may not be the same size or format as the vidoe in your camcorder.
In fact, depending on which model of camcorder you're using, the MP4 files from your camcorder may not work in Premiere Elements. Video from Flip cameras and other flash-memory based cams will need to be converted before you bring them into Premiere Elements.
I have a Sanyo and reading the files does not appear to be a problem. I used the Share to Personal Computer.
I just tried using the Share to Blu Ray and that did not work. I don't have one and it did not let me select a folder to save to or any way to save in the absense of a burner.
Next I tried the IPod and finally got it to work. Seems a bit obsure.
Unlike DVD-Video, PrE does not allow for BD to Burn to Folder, only to a BD. There are other programs that will allow you to Import your BD-compliant Exported file and then Burn to Folder. I use Adobe Encore, but it is only available with PrPro and not a stand-alone. Do not know that DVD Architect can do this, but would assume that it can.
Note that the same video/audio stream can fit inside an MOV and an MP4. The file type is just a container.
Click Share, select the Personal Computer option. Select QuickTime. Click Advanced. Under video, set the resolution to 1280x720. Set your bitrate. This determines how large your file will be. If you set it too low, the video will look lousy. Start with 5,000 or so. Make sure the codec is set to H.264. Under Audio, set the sampling rate to the rate of your project. Now you can save the video as an H.264/AAC MOV file.
If you REALLY want it to be an MP4, just get a program called Yamb. Start the program and click Editing. Click on the option that says "Click to extract streams from AVI/MP4/MOV/TS files." Open the MOV file. Now click the option to extract to an MP4. OK it, and you now have a 1280x720 MP4.