My ASP.NET MVC (C#) application is using Uploadify to upload files to Amazon S3 using the SDK for .NET, but it shows incorrect upload progress.

When I upload a file directly to our server using Uploadify it works fine. However, when I upload a file using Amazon S3 TransferUtility.Upload method, the progress bar shows 100% completion quickly, but I need to wait for a long time to attain Uploadify's onComplete event.

Code is shown below

C# code:

using (transferUtility = new TransferUtility(AWSAccessKey, AWSSecretKey))
{
try
{
TransferUtilityUploadRequest request = new TransferUtilityUploadRequest();

request.WithBucketName(AWSBucket)
.WithKey(folderKey)
.WithTimeout(5 * 60 * 1000)
.WithInputStream(uploadFileStream);

request.WithCannedACL(S3CannedACL.PublicRead);

transferUtility.Upload(request);
}
catch (AmazonS3Exception amazonS3Exception)
{
throw amazonS3Exception;
}
}


JavaScript code:

jQuery(document).ready(function () {
var allowdfileext='*.doc;*.docx;*.pdf;'
var extarray=allowdfileext.split(';');

jQuery('#proposalUploadFile').uploadify({
'uploader': '/Content/uploadify/uploadify.swf',
'script': '/File/Upload',
'folder': '/uploads',
'buttonImg':'/Content/uploadify/upload-file.jpg',
'cancelImg': '/Content/uploadify/cancel.png',
'auto': true,
'height': '25',
'width': '95',
'wmode':'transparent',
'sizeLimit': '20971520',
'onComplete': fileUploaded,
'multi': false,
'scriptData': {
'saveToFolder': 'Temp',
'fileextension':'*.doc;*.docx;*.pdf;',
'subdomain':'qa','saveInLocal':'True'
},
'fileExt':'*.doc;*.docx;*.pdf;',
'fileDesc':'Files (*.doc;*.docx;*.pdf;)',
'onAllComplete': fileUploadCompleted,
'onError' : function(event, ID, fileObj, errorObj) {
var r = '<br />ERROR: ';

switch(errorObj.info) {
case 405:
r += 'Invalid file type.';
break;
case 406:
r += 'Some other error.';
break;
default:
r += 'Some other error.';
break;
}
}
});
});

Why isn't the progress bar updating like I'm expecting it to?