MVC 5 get value of CheckBox Checked in controller with Ajax.BeginForm - asp.net-mvc

Question

I use MVC 5 and I try to get the value of the checkbox checked in the controller but so far it always return null.
Here is my code:
In View
#using (Ajax.BeginForm("Delete",
"User",
new AjaxOptions
{
HttpMethod = "POST",
InsertionMode = InsertionMode.Replace,
UpdateTargetId = "table",
OnSuccess = "Success",
OnFailure = "Fail"
}))
{
Add
<button type="submit">Delete</button>
<div id="table">
#{Html.RenderPartial("_UserTable", Model);
</div>
}
My Partial View
<table>
<thead>
<tr>
<th></th>
<th>Name</th>
<th>Email</th>
</tr>
</thead>
<tbody>
#foreach (var item in Model)
{
<tr>
<td>
<input type="checkbox" namespace="userCheck" value="#Html.DisplayFor(modelItem => item.UserName)"/>
</td>
<td>
#Html.DisplayFor(modelItem => item.UserName)
</td>
<td>
#Html.DisplayFor(modelItem => item.Email)
</td>
</tr>
}
</tbody>
</table>
And My Controller
public ActionResult
Delete(string[] userCheck)
{
for (int ix = 0; ix < userCheck.Length; ix++)
{
// do something with userCheck[ix]
}
return Index();
}
My button works and go to the Delete Action but userCheck is always null.
How can I get the value of the multiple checkbox?
Thanks