Resizing an image in photoshop is failing.

I'm sure I'm missing something but I'm attempting to resize an Image in photoshop with scripting and I can't get it to resize or save.  I believe I have an error in my resizeImage but I'm not sure what it is.  I believe I followed the guide correctly.

function saveFileJpg(saveFolder, fileName) {
    var doc = app.activeDocument;
    var v = new UnitValue(800, "px")

    doc.resizeImage(v, null, 72, ResampleMethod.NONE);

    var jpgFile = new File(saveFolder + '/' + fileName.replace(".psd", ".jpg"));
    var jpgOptions = new JPEGSaveOptions();

    jpgOptions.quality = 12;

    doc.saveAs (jpgFile, jpgOptions, true, Extension.LOWERCASE)
}