Selected Value not being set in a Dropdown List from a SelectList

Dropdown lists in MVC...basically the bane of my existence...

I've seen numerous topics on this exact issue, but everything I've found on here and around the Internet haven't solved my issue.

A bit of background first: I have a page that allows users to edit a record. One of those fields on the edit page is a Dropdown list filled with clients. To get to the edit page, the user clicks on an Edit link from another page with a table of records on it. When they get to the edit page, the form is populated with the information from the selected record to edit. Besides a login screen, it's probably one of the most basic and common features to ANY website that moves data around.

So, here's the code from the View:

@Html.DropDownList("ClientsDropdown", (IEnumerable<SelectListItem>)ViewBag.ClientsDropdown, "Select a Client")

And here's the code in the Controller:

[HttpGet]
    public ViewResult Details(int id, int pageNumber = 1)
    {
        Invoice invoice = db.Invoices.Find(id);
        FillClientDropdown(invoice);
        var model = new InvoiceDetailsModel() { Invoice = invoice, PageNumber = pageNumber };
        return View(model);
    }

And FillClientDropdown(invoice) calls:

private void FillClientDropdown(Invoice invoice)
    {
        var clientList = db
            .Clients
            .OrderBy(x => x.Name)
            .ToList()
            .Select(x => new SelectListItem
            {
                Selected = (x.ID == invoice.ClientOcrStringID),
                Text = x.Name,
                Value = x.ID.ToString()
            });

        ViewBag.ClientsDropdown = new SelectList(clientList, "Value", "Text", "Selected");
    }

I've already confirmed that clientList does in fact get a nice list of clients from the database, and that the proper SelectListItem has the "Selected" attribute set to True.

But when I load up the page and Inspect the Dropdown list, this is what I get:

<select id="ClientsDropdown" name="ClientsDropdown">
<option value="">Select a Client</option>
<option value="1">Test Client 1</option>
<option value="2">Test Client 2</option>

I would have guessed that creating a new SelectList would also add in a Selected="something" value for each option, but that doesn't seem to be the case.

Any help with this issue would be greatly appreciated, as it's rather frustrating to know that I could have done this in about 3 minutes if I were able to use Web Forms...

UPDATE

Looks like I got it working!

Here's what I did: I already had an InvoiceDetailsModel to work with, so I added:

public SelectList ClientList { get; set; }

Then, in my InvoiceController, I changed up my Details a bit:

[HttpGet]
    public ViewResult Details(int id, int pageNumber = 1)
    {
        Invoice invoice = db.Invoices.Find(id);
        var clientList = db
            .Clients
            .OrderBy(x => x.Name)
            .ToList()
            .Select(x => new SelectListItem
            {
                Text = x.Name,
                Value = x.ID.ToString()
            });
        var model = new InvoiceDetailsModel() { Invoice = invoice, PageNumber = pageNumber };
        model.ClientList = new SelectList(clientList, "Value", "Text", model.Invoice.ClientOcrStringID);
        return View(model);
    }

to take advantage of my addition to the InvoiceDetailsModel. Finally, in my view, I changed my Dropdown to this:

@Html.DropDownListFor(model => model.Invoice.ClientOcrStringID, Model.ClientList, "Select a Client")

I'm hoping this helps someone...anyone in the future.