Trouble changing Camera RAW settings in Javascript (worked in CS5, but not CS6)

Question

I just upgraded to Master Collection CS6 from Production Premium CS5, and CameraRAWOpenOptions settings in scripts that I had working in Photoshop CS5 (64-bit) using Extendscript CS5 are no longer working with Photoshop CS6.  I get no error messages, but the settings I specify in the scripts (for example, CameraRAWOpenOptions.exposure=2.00) do not take effect when the image is opened.  Other Photoshop properties and actions within my script are working correctly.
Note that this is an issue in Photoshop CS6.  I can use Extendscript CS5 or CS6, and the result is the same.
Here is the way I am changing the settings in my script:
var RawOptions = new CameraRAWOpenOptions;
//RawOptions.settings=CameraRAWSettingsType.CUSTOM;
//RawOptions.settings=CameraRAWSettingsType.SELECTEDIMAGE;
RawOptions.settings=CameraRAWSettingsType.CAMERA;
RawOptions.exposure=+2.00;
RawOptions.vignettingAmount = 0;
RawOptions.vignettingMidpoint = 0;
RawOptions.contrast = 50;
RawOptions.saturation = 0;
RawOptions.shadows = 0;
RawOptions.luminanceSmoothing = 0;
var JPGopts = new JPEGSaveOptions;
JPGopts.quality = JPEGquality;
//Perform the loop through the files
app.open(testListing[0], RawOptions, false);
app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);
for (var nfile = nstart; nfile < nstop; nfile++)
    app.open(testListing[nfile], RawOptions, false);
    FnameSave = new File(SavePath+"/"+testListing[nfile].name);
    app.activeDocument.saveAs(FnameSave, JPGopts, false, Extension.UPPERCASE);
    app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);

Answer 1

I found a few of them actually work.
CameraRAWOpenOptions.tint=0; // works (-150 to 150)
CameraRAWOpenOptions.temperature=5500; // works (2000 to 50000)
CameraRAWOpenOptions.luminanceSmoothing = 0; // works 0 to 100
CameraRAWOpenOptions.saturation=50; // works =100 to 100
CameraRAWOpenOptions.vignettingAmount=0; //works -100 to 100
CameraRAWOpenOptions.vignettingMidpoint=0; //works -100 to 100
These ones do not work:
CameraRAWOpenOptions.brightness=0; // does not work (0 to 150)
CameraRAWOpenOptions.contrast=0; // does not work (-50 to 100)
CameraRAWOpenOptions.exposure = 0; // does not work (-4.0 to +4.0)
CameraRAWOpenOptions.shadows=0; // (0 to 100) does not work
CameraRAWOpenOptions.whiteBalance=WhiteBalanceType.SHADE; // does not work
I noticed that, doing File-->File Info--> "Advanced" tab-->expand "Camera Raw Properties" that the ones that do not work have mostly either been removed (brightness) or had "2012" added to their names in the XMP in the conversion from CS5 to CS6.
It appears the mapping from Javascript objects/properties to how Photoshop knows them is broken with the new version.  Is there any way to fix this?
Is there an alternate way to do this by going through XMP?
Unfortunately, I'm wanting to use "exposure", which is one of the ones that is broken.  My main script sets a custom exposure for each image (trying to smooth out EV jumps between successive images in a sunset time lapse).