Accessing the class object from the Dependancy Proprty Changed Callback - wpf

Question

I am having trouble accessing a lable in my custom WPF control. I have implemented the PropertyChangedCallback but from there I can't get access to the class.
The class is a simple control with a lable (Name="lblDataName") that I want to change the text to match the DataName property.
Here is the code behind:
Public Class DataNameControl
Public Property DataName As String
Get
Return GetValue(DataNameProperty)
End Get
Set(ByVal value As String)
SetValue(DataNameProperty, value)
End Set
End Property
Public Shared ReadOnly DataNameProperty As DependencyProperty = _
DependencyProperty.Register("DataName", _
GetType(String), GetType(GraphData), _
New PropertyMetadata("KPI", AddressOf OnDataNameChanged))
Public Shared Function OnDataNameChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs) As String
Dim dnc As DataNameControl = CType(d, DataNameControl)
dnc.lblDataName.Text = e.NewValue.ToString
'' I want to access the lable on my class right here.
Return e.NewValue.ToString
End Function
End class
I would hope that setting the property in XAML would update the label accordingly, but nada!
<Controls:DataNameControl DataName="BCWP" Margin="0"/>
There are tons of answer on how to change the property itself, but none seem to answer this specifically, and if been tinkering for 20 hours on this one issue. Time ask for help!

Answer 1

The third parameter of the Register method is wrong. It must be GetType(DataNameControl) instead of GetType(GraphData):
Public Shared ReadOnly DataNameProperty As DependencyProperty = _
DependencyProperty.Register( _
"DataName", GetType(String), GetType(DataNameControl), _
New PropertyMetadata("KPI", AddressOf OnDataNameChanged))
The PropertyChangedCallback should not return a value:
Public Shared Sub OnDataNameChanged( _
ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
Dim dnc As DataNameControl = CType(d, DataNameControl)
...
End Sub

Answer 2

Newbies (like me),
If you are reading this looking for a solution to your problem, the primary lesson here is, "make sure you are passing the proper parameters to your property registration." the VS widget will sort of help you through the process but only the first time, after that, if you change the name of your class, VS won't automagically change the class in the registration - that was the source of my problem.
SO a generic example based on the widget code added by VS2013 :
Public Shared ReadOnly Prop1Property As DependencyProperty = _
DependencyProperty.Register("Prop1", _
GetType(String), GetType(Window1), _
New PropertyMetadata(Nothing))
Prop1Property is your property name plus the suffix property.
"Prop1" is that property name.
1st GetType(String) is the variable type is the type of YOUR property. VS enters string as a default.
2nd GetType(Window1) is simply the class in which your property exists. VS enters "Window1" as a default. This is likely never correct and its not linked to anything else in the widget so you will have to change it yourself. I say simply, but this is where I messed up.
New PropertyMetadata has 6 overloads depending on how you planning on handling the values of the property.
In this case, "Nothing" explicitly states the default value is nothing.
Options include Default values, Property change callbacks, CoerceValueCallback and an IsValidValueCallback. All of that is a little beyond, my problem. I have to sort of figure them out to get my code working, so if anybody has questions, reply and I might add some info.
If you are new to Dependency Properties, which the two 10-minute videos.
Youtube: WPF Tutorial 21 - Dependency Properties
They are simple and enough to get you up and running.