Highlight required field in detailview

Hello Pete,
Can you please provide me with your sample, because it's difficult to find what's wrong with your code without debugging it?
In any case, I see that you are trying to set the BackColor of the TableEx control. I don't think that this is the best way to do what you want.
It's better to process ASPxPropertyEdititor objects only (FindItem(name) as ASPxPropertyEditor) and then set the color of their Editor object.
Alternatively, you can use the approach I used in the How to highlight the focused editor in DetailView example, to process ASPxWebControl objects only (check out the HighlightFocusedLayoutItemDetailViewController class for more details).
I suggest you implement one of these approaches in your sample and attach it here if it doesn't work. Then I could help you further.
See Also:
http://documentation.devexpress.com/#Xaf/CustomDocument2729

Update
Here is a C# example for version 14.1.6:

C#
public class ViewController1 : ObjectViewController<DetailView, Contact> {  
    protected override void OnActivated() {  
        base.OnActivated();  
        ((WebLayoutManager)View.LayoutManager).ItemCreated += ViewController1_ItemCreated;  
    }  
    void ViewController1_ItemCreated(object sender, ItemCreatedEventArgs e) {  
        PropertyEditor editor = e.ViewItem as PropertyEditor;  
        if (editor != null && editor.PropertyName == "FirstName") {  
            ((LayoutItemTemplateContainer)e.TemplateContainer).Caption = "Some custom text1";  
            if (e.TemplateContainer.CaptionControl != null) {  
                CustomizeCaptionControl(e.TemplateContainer.CaptionControl);  
            } else {  
                e.TemplateContainer.Load += TemplateContainer_Load;  
            }  

        }  
    }  
    void TemplateContainer_Load(object sender, EventArgs e) {  
        LayoutItemTemplateContainerBase templateControler = (LayoutItemTemplateContainerBase)sender;  
        templateControler.Load -= TemplateContainer_Load;  
        CustomizeCaptionControl(templateControler.CaptionControl);  
    }  
    private void CustomizeCaptionControl(WebControl captionControl) {  
        captionControl.BackColor = Color.Red;  
    }  
    protected override void OnDeactivated() {  
        base.OnDeactivated();  
        ((WebLayoutManager)View.LayoutManager).ItemCreated -= ViewController1_ItemCreated;  
    }  
}  

Thanks,
Dennis