Warum funktioniert das Folgende nicht?

Zwei Formen; der erste ruft den zweiten an. Auf dem zweiten Formular befindet sich eine DataGridView. Sie enthält keine Spalten. Sie werden vom Programm zusammen mit einer DataGridViewButtonColumn hinzugefügt.

Der erste Aufruf von Form2 funktioniert einwandfrei. Beim zweiten Aufruf haben die Schaltflächen jedoch keinen Text.

' The first form - has one button, which calls Form2
Pu,blic Class Form1
    Friend fruit As New List(Of Fruit)

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        fruit.Add(New Fruit("Apple", "Red"))
        fruit.Add(New Fruit("Orange", "Orange"))
        fruit.Add(New Fruit("Banana", "Yellow"))
        fruit.Add(New Fruit("Melon", "Red"))
        fruit.Add(New Fruit("Pear", "Green"))
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Form2.ShowDialog()
    End Sub
End Class


Public Class Fruit
    Public Property name As String
    Public Property colour As String
    Public Sub New(newName As String, newColour As String)
        name = newName
        colour = newColour
    End Sub
End Class

Code für das zweite Formular ist:

' Form2 has a button which closes the form, and a DataGridView
Public Class Form2
    Dim dataGridViewButtonColumn1 As DataGridViewButtonColumn
    Dim setupAlready As Boolean = False

    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        dataGridViewButtonColumn1 = New DataGridViewButtonColumn
        DataGridView1.DataSource = Form1.fruit
        With dataGridViewButtonColumn1
            .Name = "ButtonCol"
            .UseColumnTextForButtonValue = False
        End With
        If Not setupAlready Then
            DataGridView1.Columns.Add(dataGridViewButtonColumn1)
        End If
        For i As Integer = 0 To 4
            DataGridView1.Rows(i).Cells("ButtonCol").Value = "Hello"
        Next
        setupAlready = True
    End Sub

    Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) _
                Handles DataGridView1.CellContentClick
        Debug.Print(String.Format("Col={0}, Row={1}, ColName={2}", e.ColumnIndex, e.RowIndex, DataGridView1.Columns(e.ColumnIndex).Name))
        If (DataGridView1.Rows.Item(e.RowIndex).Cells("ButtonCol").Value Is "Hello") Then
            DataGridView1.Rows.Item(e.RowIndex).Cells("ButtonCol").Value = "GoodBye"
            DataGridView1.Rows(e.RowIndex).DefaultCellStyle.BackColor = Color.LightGreen
        End If
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Me.Close()
    End Sub
End Class