List of (myClass) troubles

It does not load the list

It does not load the list because as the first warning/error tells you there is a null reference exception occurring on line 8. This is corrected by what the others have mentioned. Make sure you are not using On Error in your code. That old VB6-style of error handling should be abandoned in favor of Try/Catch. Try/Catch is easier to follow/understand and debug.

Let's see...
Kaufmed nailed it.  I am an old VB6 guy who is trying to make the transition to .net.  Trying, and mostly failing.  I an not using OnError.  I do not use Try/catch here.  But it would be nice to get an error so I could know something was wrong.
 
Tried what GHz suggested but it did not change anything.  

I'm not sure exactly what I should do based on what Olemo said.

I think most has been answered, but I will try to add something:

I think in VB6, Doing 'Dim thing As MyClass' would create a reference to 'the' MyClass instance.

In .NET, you are only defining a variable to do this. You always have to create a new instance of a class if you want to use it. So in your first post you are only defining the variable but not initializing it to an actual instance.

You can do either:

Dim instance As MyClass = New MyClass()

Or:

Dim instance As New MyClass()

Note: you can omit the () in VB.NET when you are using the default constructor
Note: my personal preference is the form "Dim instance As MyClass = New MyClass()" as it is more explicit (also it looks more like C# which is my preferred language :))

Hope this helps!

*No Points*

Proof of concept project based on other experts input (Note: My table columns are not the same as yours so the column identifiers are off, same with my table identifier in the dataset):

Public Class Form1
	Private PatientList As List(Of Patient)
	Private Sub OnLoad(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
		PatientList = New List(Of Patient)
		PatientsTableAdapter.Fill(PatientsDataSet.Patients)
		Dim aPatient As Patient
		For Each row In PatientsDataSet.Tables(0).Rows
			ListBox1.Items.Add(String.Format("{0}, {1}", row(3), row(2)))
			aPatient = New Patient() With {.ID = row(0), .ExternalID = row(1), .Name = String.Format("{0}, {1}", row(3), row(2))}
			If Not aPatient Is Nothing Then
				PatientList.Add(aPatient)
			End If
		Next
	End Sub
End Class

Public Class Patient
	Public Property ID() As Integer
	Public Property ExternalID() As String
	Public Property Name() As String
End Class

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Produces the following output -And shows the following in the PatientList --saige-

And if you really want to get fancy, why create a new listbox item for each patient, when you can just use the patient list as the datasource for your listbox control:

Public Class Form1
	Private PatientList As List(Of Patient)
	Private Source As New BindingSource

	Private Sub OnLoad(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
		PatientList = New List(Of Patient)
		PatientsTableAdapter.Fill(PatientsDataSet.Patients)
		Dim aPatient As Patient
		For Each row In PatientsDataSet.Tables(0).Rows
			aPatient = New Patient() With {.ID = row(0), .ExternalID = row(1), .Name = String.Format("{0}, {1}", row(3), row(2))}
			If Not aPatient Is Nothing Then PatientList.Add(aPatient)
		Next
		Source.DataSource = PatientList
		ListBox1.DataSource = Source
	End Sub
End Class

Public Class Patient
	Public Property ID() As Integer
	Public Property ExternalID() As String
	Public Property Name() As String

	Public Overrides Function ToString() As String
		Return Name
	End Function
End Class

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Produces the same output as above -And since I overrided the ToString method of the Patient class, now the PatientList shows --saige-

Try this :

    Private PatientList As List(Of Patients) = Nothing
    Private Sub frmPatientLookup_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        PatientList = New List(Of Patients)
        Me.PatientsTableAdapter.Fill(Me.PatientsDataSet.Patients)
        For Each r In PatientsDataSet.Tables(2).Rows
            lstPatients.Items.Add(r(2) & ", " & r(1))
            PatientList.Add(New Patients With {.Name = r(2).ToString & ", " & r(1).ToString, _
                                               .ID = r(0).ToString, .ExternalID = r(3).ToString})
        Next
    End Sub

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Qlemo proposed the resolution - https://www.experts-exchange.com/questions/28588284/List-of-myClass-troubles.html?anchorAnswerId=40523306#a40523306

Kaufmed provided clarifying assistance - https://www.experts-exchange.com/questions/28588284/List-of-myClass-troubles.html?anchorAnswerId=40523551#a40523551

Ghz provided an example - https://www.experts-exchange.com/questions/28588284/List-of-myClass-troubles.html?anchorAnswerId=40523364#a40523364

-saige-