MVC Session Not Showing in PartialView - asp.net-mvc

Question

I am doing a post back to a controller and setting Sessions. After they are set, it shows up in the first tab, but when I click next tab that loads another partialview, I do not see sessions set.
order.cshtml with Tabs...
<div id="tabs">
<ul class="nav nav-tabs">
<li>General</li>
<li>Item</li>
<li>Total</li>
</ul>
<div id="tabs-1">
#{Html.RenderPartial("_Partial_General_Tab", Model.GeneralTab);}
</div>
<div id="tabs-2">
#{Html.RenderPartial("_Partial_Item_Tab", Model.ItemTab);}
</div>
<div id="tabs-3">
Content for Tab 3 goes here.<br />
</div>
</div>
Tab 1
#model Mvc5.Models.ORDERMetadata
#{
var ordernumber = (int)Session["Order_Number"];
var princid_session = Session["PrincId"];
var custid_session = Session["CustId"];
}
OrderNumber: #ordernumber <br />
PrinicId: #princid_session <br />
CustID: #custid_session <br />
#using (Ajax.BeginForm("Edit", "Order",
new AjaxOptions
{
HttpMethod = "POST",
InsertionMode = InsertionMode.Replace,
UpdateTargetId = "target"
}))
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
Enter model data here....
<button id="editorder" type="submit" class="btn btn-default">Save</button>
}
Tab 2
#model Mvc5.Models.ORDER_DETAILSMetadata
#{
var ordernumber = (int)Session["Order_Number"];
var princid_session = Session["PrincId"];
var custid_session = Session["CustId"];
}
OrderNumber: #ordernumber <br />
PrinicId: #princid_session <br />
CustID: #custid_session <br />
#using (Ajax.BeginForm("Items", "Order",
new AjaxOptions
{
HttpMethod = "POST",
InsertionMode = InsertionMode.Replace,
UpdateTargetId = "target"
}))
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
Enter model data here....
<input type="submit" value="Add" class="btn btn-default" />
}
Edit Controller
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(ORDERMetadata model)
{
try
{
// update order
....
db.Entry(order).State = EntityState.Modified;
db.SaveChanges();
Session.Clear();
Session["Order_Number"] = model.Order_Number;
Session["PrincId"] = model.Princ_ID;
Session["CustId"] = model.Cust_ID;
return PartialView("_Partial_General_Tab", model);
}
catch (DbEntityValidationException ex)
{
return RedirectToAction("Index", "Error");
}
}