Image Resize... wont resize

I have been using the image uploader for quite some time.... and have now upgraded to version 6,1,4,0.

I would like to set the maximum sizes of my images when they upload to 400 pixels. however it doesnt appear to be uploading them to the server and setting the images as the required size.

//Configure file mask to upload JPEG images only.

iu.addParam("FileMask", "*.jpeg;*.jpg;*.jpe");

//Set image size restrictions.

iu.addParam("MinImageWidth", "360");

iu.addParam("MinImageHeight", "360");

//Configure thumbnail settings.

iu.addParam("UploadThumbnail1FitMode", "Fit");

iu.addParam("UploadThumbnail1Width", "500");

iu.addParam("UploadThumbnail1Height", "400");

iu.addParam("UploadThumbnail1JpegQuality", "90");

are the parameters im settings. is there a way to lock it down so all images uploaded to the server end up at 400 pixels maximum ?

thanks in advance