codeigniter upload an image file error - ajax

Question

please help me with this error. I have a javascript that i want to append a single image file to my form and i want to send the form data into ajax.
Here is my code:
<form id="frm_product" class="form-horizontal" enctype="multipart/form-data">
<div style="position:relative;">
<input type="file" name="addfiles" id="addfiles">
<span class='label label-info' id="upload-file-info"></span>
</div>
<br>
<div class="form-group">
<label for="cat_name">Product Name: </label>
<input type="text" class="form-control" name="prod_name">
<span class="error prod_name"></span>
</div>
<div class="form-group">
<label for="cat_desc">Description: </label>
<input type="text" class="form-control" name="prod_desc">
<span class="error prod_desc"></span>
</div>
<div class="form-group">
<label for="cat_desc">Price: </label>
<input type="text" class="form-control" name="prod_price">
<span class="error prod_price"></span>
</div>
<div class="form-group">
<label for="cat_desc">Category: </label>
<select class="form-control" name="prod_cat">
<?php foreach($data as $category){ ?>
<option value="<?php echo $category->id; ?>"><?php echo $category->name; ?></option>';
<?php } ?>
</select>
<span class="error prod_cat"></span>
</div>
</form>
here is my ajax code where i want to append a single file:
function submitProduct() {
var formData = new FormData($("#frm_product")[0]);
formData.append('image', $("#addfiles")[0].files);
$.ajax({
url : siteurl+"/product/addproduct",
type: "POST",
data: formData,
dataType: "JSON",
contentType: 'multipart/form-data',
processData: false,
contentType: false,
cache: false,
success: function(resp) {
$('.error').html('');
if(resp.status == false) {
$.each(resp.message,function(i,m){
$('.'+i).text(m);
});
}
else if(resp.status == true) {
$('#addProduct').modal('hide');
$('#frm_product')[0].reset();
alert("Successfully Added");
}
}
});
}
when i do upload file it says error:
you didn't select a file to upload