MVC3 File upload button

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MVC

jQuery

I am new to MVC hope someone can help me out.
In my project on a pop up modal I have a textbox and file control (along with Upload button).

Index.cshtml

@using (Ajax.BeginForm("AddLoadDtl", "LoadDetail", FormMethod.Post, new AjaxOptions { HttpMethod = "post", UpdateTargetId = "AddLoadDialog", LoadingElementId = "AdddivProcessing", OnSuccess = "ResetControls" }, new { id = "AddLoadDtlForm", enctype = "multipart/form-data" }))
{

<div id="AddLoadDtl" style="background: #fef9f3; color: #5a5a5a; font-family: Arial; font-size: 9pt;">
        <table style="width: 100%; background: #fef9f3; color: #5a5a5a; font-family: Arial; font-size: 9pt;">
            <tr>
                <td>
                    <div class="box-con" style=" background: #fef9f3; color: #5a5a5a; font-family: Arial; font-size: 9pt;">
                        <table style="width: 100%;">
                            <tr>
                                <td width="20%">
                                    <span>Number</span>
                                    <br />
                                    @Html.Hidden("MarkNumber", (string)ViewBag.MarkNumber)
                                    @Html.TextBoxFor(m => m.Number, new { maxlength = 6, @class = "MarkDirty ValidateMaxLength" })
                                </td>   
</tr>                             
<tr>
                                <td >
                                    <span>Upload</span>
                                    <br />
                                    <input type="file" id="fileToUpload" name="file" />                            
                                    
                                    <input type="submit" name="command" id="btnSubmit" value="Upload" /><span class="field-validation-error" id="spanfile"></span>
                                </td>
                            </tr>

<input id="btnSave" type="submit" name="command" value="Save"  önclick="OnSubmit();" />
                                    <input id="btnCancel" type="button" value="Cancel"  önclick="OnCancel();"/>

HomeController.cs

public ActionResult AddLoadDtl(Load LoadModel, HttpPostedFileBase file, string command)
        {
if(command == "Upload")
{
 ....
}
else
{
...
}
}

So here name="command" is given in order to handle the "submit" type for the buttons (Upload and Save button). The issue here is HttpPostedFileBase file is returning null. When I give name="file" value for the Upload button then there is no action performed when I click on Upload button, breakpoint is not hitting the method.

Please provide some suggestion and direct me in the right way to get this issue resolve.

Thanks in advance.