In WPF/C# 2010 how do I make a button disappear if a related data object is null?

I have a screen that I use to show data from a data table. The XAML bindings are working and it displays fine. However, next to one data field, I have a button that I want to use for other things. My problem is that I don't want the button to show if the data field is null or empty. Below is snippets of the XAML and data object code that I am using.

XAML for the button:

I am starting out with the button hidden.

Here is the XAML that covers the style "DetailButton":

Here is the data object code that sets PplOlderFlag:

        _bOlderFlag = (_sPplOlderInfo.Length > 0);

    public bool PplOlderFlag
    {
        get
        {
            return _bOlderFlag;
        }
    }

As I s开发者_Go百科aid, the binding (PplOlderInfo) is working and show up fine. But the button is still there when the PplOlderInfo is null or empty.

I can set the Visibility of button in the code behind easy enough but it just seems like it would be really slick if I could make it work in the XAML.

Any ideas as to what I am leaving out or what I am doing wrong?

---

Shouldn't the type of PplOlderFlag be of type System.Windows.Visibility?

In my test app, if I make an equivalent property of type System.Windows.Visibility, I can make the button visible or invisible as required.

Edit:

From your code example, I would implement as:

public System.Windows.Visibility PplOlderFlag
{
    get
    {
        return _bOlderFlag ? System.Windows.Visibility.Visible : 
                             System.Windows.Visibility.Hidden;
    }
}