problem with UncheckUploadedFiles()

iu.addParam("UncheckUploadedFiles", "false");

<script type="text/javascript">	
				
//<![CDATA[
//Create JavaScript object that will embed Image Uploader to the page.
var iu = new ImageUploaderWriter("ImageUploader1", 550, 490);

//For ActiveX control full path to CAB file (including file name) should be specified.
iu.activeXControlCodeBase = "javascripts/ImageUploader4.cab";
iu.activeXControlVersion = sc.activeXControlVersion;

//For Java applet only path to directory with JAR files should be specified (without file name).
//iu.javaAppletCodeBase = "javascripts/";
iu.javaAppletCodeBase = "../javascripts/";
//sc.javaAppletCodeBase = "M:/dev/haystack2/Haystack/public/javascripts/";
iu.javaAppletCached = true;
iu.javaAppletVersion = sc.javaAppletVersion;

iu.showNonemptyResponse = "off";

//Configure appearance and behaviour.
iu.addParam("PaneLayout", "TwoPanes");
iu.addParam("FolderView", "Details");
//iu.addParam("FolderView", "Details");
iu.addParam("UploadView", "Details");
iu.addParam("PreviewThumbnailSize", "100");
iu.addParam("ShowButtons", "false");
iu.addParam("ShowSubfolders", "true");
iu.addParam("ShowDescriptions", "false");
iu.addParam("ShowContextMenu", "true");
iu.addParam("ShowDebugWindow", "true");
iu.addParam("AllowMultipleRotate", "true");

//Configure colors.
iu.addParam("PaneBackgroundColor", "#ffffff");
iu.addParam("BackgroundColor", "#ffffff");
iu.addParam("PreviewThumbnailActiveColor", "#f8b330");
iu.addParam("PreviewThumbnailInactiveColor", "#eeeeee");

//Hide tree pane.
iu.addParam("TreePaneWidth", "-1");

//Allow upload not only files, but also entire folders.
//iu.addParam("AllowFolderUpload", "true");

//Single or multiple file selection.
//iu.addParam("AllowMultipleSelection", "false");

//Link ImageUploader with ShellComboBox.
iu.addParam("AdditionalFolderNavigator", "ImageUploader1");


//Configure file mask to display images only.
iu.addParam("FileMask", "*.jpg;*.jpeg;*.jpe;*.gif;*.png;*.tif;*.tiff;*.psd");

// Config EXIF Settings
iu.addParam("ExtractExif", "ExifDateTime;ExifDateTimeOriginal;ExifCopyright;ExifGpsDateStamp;ExifGpsLatitudeRef;ExifGpsLatitude;ExifGpsLongitudeRef;ExifGpsLongitude;ExifImageDescription;ExifImageUniqueID;ExifOrientation;ExifRelatedSoundFile;ExifUserComment;ExifSubjectLocation;ExifSubjectArea;ExifMake;ExifModel;");
iu.addParam("ExtractIptc", "IptcByline;IptcCredit;IptcSource;IptcDateCreated;IptcCopyrightNotice;IptcCaption;IptcSpecialInstructions;IptcKeyword;");



//Configure thumbnail settings.
iu.addParam("UploadThumbnail1Width", "32");
iu.addParam("UploadThumbnail1Height", "32");
iu.addParam("UploadThumbnail1JpegQuality", "60");
//iu.addParam("UploadThumbnail1CopyExif", "true");

//Configure upload settings.
iu.addParam("Action", "upload");
iu.addParam("FilesPerOnePackageCount", "5");
iu.addParam("AutoRecoverMaxTriesCount", "3");
iu.addParam("AutoRecoverTimeOut", "10000");

//Configure Image Uploader to rotate photos automatically 
//according to the orientation stored in EXIF metadata.
iu.addParam("EnableAutoRotate", "true");
//#TODO: source images are not rotated, thumbnails are

//Append the form with total file size to the upload.  
//iu.addParam("AdditionalFormName", "Form1");

//Whichcraft Prepare
iu.addParam("UploadThumbnail1FitMode", "fit");
iu.addParam("UploadThumbnail1CopyExif", "true");
iu.addParam("AllowFolderUpload", "true");
iu.addParam("UncheckUploadedFiles", "false");
iu.addParam("UploadSourceFile", "false");



//Add event handlers.
iu.addEventListener("UploadFileCountChange", "ImageUploader_UploadFileCountChange");
iu.addEventListener("Progress", "ImageUploader_Progress");
iu.addEventListener("BeforeUpload", "ImageUploader_BeforeUpload");


iu.fullPageLoadListenerName = "FullPageLoad";

//Tell Image Uploader writer object to generate all necessary HTML code to embed 
//Image Uploader to the page.
iu.writeHtml();
//]]>
				</script>
				
				
	<script type="text/javascript">
//<![CDATA[	
//This UploadFileCountChange event handler displays total size of all files selected for upload.
function ImageUploader_UploadFileCountChange(){
	var imageUploader1 = getImageUploader("ImageUploader1");
	if (imageUploader1){
		document.getElementById("TotalSourceFileSize").value = Math.ceil(imageUploader1.getTotalFileSize() / 1024);
	}
}

//This Progress event handler demonstrates an alternative way to 
//redirect upon upload (instead of RedirectUrl property).

function ImageUploader_send() 
{
    setTimeout("getImageUploader('ImageUploader1').Send()", 500);
}

var WasUpload = false;
//var WasUpload = true;
function ImageUploader_Progress(Status, Progress, ValueMax, Value, StatusText)
{

	if (Status=="COMPLETE")
	{
       alert('preparing to filter selection list');
       if (WasUpload)
	   {
    		WasUpload = false;
            document.getElementById('btnUpload').innerHTML=('Find');			
    		window.location = 'gallery'; 
    		return;
	   }
	   // Remove unwanted files from upload list

    var iu = getImageUploader("ImageUploader1");
    alert("Upload file count="+iu.getUploadFileCount());
    value = getImageUploader("ImageUploader1").getUncheckUploadedFiles();
    alert("UncheckUploadedFiles="+value);
 /* 
      
	   // During next upload source files will be sent
	   iu.setUploadSourceFile("true");
	   iu.setUncheckUploadedFiles("true");
	   iu.setUploadThumbnail1FitMode("Fit");
	   WasUpload = true;
       document.getElementById('btnUpload').innerHTML=('SharePhotos');	   
       
*/         
      
    }
} 


function ImageUploader_BeforeUpload() {
    alert("Before upload event");
    var iu = getImageUploader("ImageUploader1");
    iu.setUncheckUploadedFiles("false");
    value = getImageUploader("ImageUploader1").getUncheckUploadedFiles();
    alert("UncheckUploadedFiles="+value);
    alert("BeforeUpload file count="+iu.getUploadFileCount());
}

//]]>
	</script>