I am attempting to use a `ComboBox.SelectedItem` to filter on a `DataGrid`, however I am having an issue accessing the `SelectedItem` as a `string`. This is what I have attempted so far;

```
foreach (ComboBoxItem cItem in departmentComboBox.ItemsSource)
{
    if (departmentComboBox.SelectedItem != null)
    {
        criteria.Add(new Predicate<EmployeeModel>(x => x.Department == departmentComboBox.SelectedItem as string));
        break;
    }
}

```

This results in an exception;

```
Additional information: Unable to cast object of type 'System.String' to type 'System.Windows.Controls.ComboBoxItem'.

```

`x.Department` is of type `string`. How can I access the `SelectedItem` correctly so that I can use it in my filtering method correctly?

EDIT: To show how the ComboBox items are added;

```
List<string> distinctList = Employees.Select(i => i.Department).Distinct().ToList();
distinctList.Insert(0, "Everyone");
distinctList.Sort();
departmentComboBox.ItemsSource = distinctList;

```