v2.5 Compiler Error

Hi, everything is working great with my clients' store, the only problem is that they cannot view their orders in the system.  When in the admin section, if you click on "View", it results in the following error:

Compiler Error Message: CS1061: 'Nop.Admin.Models.Orders.OrderModel' does not contain a definition for 'TrackingNumber' and no extension method 'TrackingNumber' accepting a first argument of type 'Nop.Admin.Models.Orders.OrderModel' could be found (are you missing a using directive or an assembly reference?)

Source File: e:\web\grafinkscom\htdocs\Administration\Views\Order\Edit.cshtml   Line: 897

I should note that we have done no customizing to the store-- except design of course.  The deployment has not been altered.

Please let me know how this can be remedied.

Thanks!

Did you do an upgrade?

Yes.  I believe 2.3 to 2.5 a few months back.

Odd.
In Edit.cshtml, if you right-click the TrackingNumber field, and choose Goto Definition, does it take you to  \src\Presentation\Nop.Web\Administration\Models\Orders\ShipmentModel.cs ?

I'm a VB.Net/Web Forms guy.  I opted to go the no-source route so I wouldn't accidentally jack up the C#/MVC code.

Going on 2 weeks now with no fix.  Anyone??