MVC Ajax - Partial view is getting values but not refreshing the Main view

See more:

C#

Ajax

MVC3

Razor

I'm new to MVC.
I have two drop-downs when we are selecting the first one we need to update the second one.
Below is my view
@model HostingManager.Models.ContractManager
@{
ViewBag.Title = "CustomCreate";
}

@Html.Partial("_GroupDDL" , Model)


@Html.Partial("SelectClient", Model)


@Html.Partial("SelectContract", Model)

Below is first Drop-down(Partial View:_GroupDDL)
@model HostingManager.Models.ContractManager

@using (Ajax.BeginForm("SelectClient", "Contracts", new AjaxOptions { UpdateTargetId = "IClients" }))
{
@Html.DropDownListFor(
m => m.SelectedGroupId,
new SelectList(Model.IGroups, "id", "name"),
string.Empty
)
}
<script type="text/javascript">
$('#SelectedGroupId').change(function () {
$(this).parents('form').submit();
});
</script>

Below is Second Drop-down(Partial View : SelectClient)
@model HostingManager.Models.ContractManager

@if (Model.IClients != null && Model.IClients.Count() > 0)
{
using (Ajax.BeginForm("SelectContracts", "Contracts", new AjaxOptions { UpdateTargetId = "IContracts" }))
{
@Html.HiddenFor(m => m.SelectedGroupId)
@Html.DropDownListFor(
m => m.SelectedClientId,
new SelectList(Model.IClients, "id", "cname"),
string.Empty
)
}
}

<script type="text/javascript">
$('#SelectedClientId').change(function () {
$(this).parents('form').submit();
});
</script>

Below is my Controller action
public ActionResult CustomCreate()
{
ContractManager CM = new ContractManager();
CM.IGroups = db.groups.ToList();
return View(CM);
}

[HttpPost]
public ActionResult SelectClient(int? SelectedGroupId)
{
ContractManager CM = new ContractManager();
CM.IClients = new List();
if (SelectedGroupId.HasValue)
{
CM.IClients = db.client.ToList();
}
return PartialView("SelectClient", CM);
}
Now The problem:
In Debugging Mode when I'm selecting the first DDL..Control is coming to second DDL with the values but the Second DDL is not appearing on the View.I mean on UI we can't see the Second DDL.

As per My Code It is calling the SelectClient of Controller but my Main View is not updating with the updated partial view.

Can anybody plz tell where the problem is..
I already added ajax script in my Layout and also enabled in web.config
I'll filter the Second DDL the Once if I can overcome this.

Thanks in Advance