How do I disable WPF CheckCombobox dropdown until triggered from another control

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WPF-Extended-Toolkit

Greatings All,

This is my first post on the board. I am a Newbie to WPF and C# programming and I have been trying my best to learn as I go. Currently I am working on a project for work and I hit a stumbling block. I have 2 Checkcombobox controls I have populated with data. The first checkcombobox has one selection item in the list that I would like to trigger the 2nd Checkcombobox to become fully active. My controls have been set to show the dropdowns when my form starts without having to click the dropdown arrow. The issue I have been having is preventing click activity in the 2nd dropdown when IsEnabled=false from my C# code file. You can still click selections in Checkcombobox 2 dropdown even though it has been disabled. In the control template I changed this line:

<ItemsPresenter x:Name="PART_ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" IsEnabled="False"/>

The control now blocks the click activity which is what I was after. The question is, how do I revert this back to an enabled state when this criteria is met?

public void Modality_Select_ItemSelectionChanged_1(object sender, Xceed.Wpf.Toolkit.Primitives.ItemSelectionChangedEventArgs e)
       {
           if (Modality_Select.SelectedItems.Contains("EMG"))
           {
               EMG_LB.IsEnabled = true;
               EMG_Type.IsEnabled = true;


           }
           else
           {

               EMG_Type.SelectedItem = null;
               EMG_LB.IsEnabled = false;
               EMG_Type.IsEnabled = false;


           }

Modality_Select is Checkcombobox 1 and EMG_Type is Checkcombobox 2.

Any help is greatly appreaciated. Please keep in mind I am still early on the learning curve, therefore easily lost.

Thank you,

Patrick