How to enable multiple image file selection in IE in php html?

Possible duplicate:
Invalid HTML5 input type file attribute that does not work in IE?

I can upload multiple images in firefox, but in IE I can upload only one image

<form id="imageUploadForm" action="<?php echo base_url();?>/index.php/product/UploadImages/<?php echo $uploadFolder;?>" method="POST" enctype="multipart/form-data" > <input name="userfile[]" id="userfile" type="file" multiple /> <input name="" id="id_uploadbtn" type="submit" class="button" value="Upload" /> </form>