I get an ArrayTypeMismatchException error with this code:

Private Sub btnCellsRand_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCellsRand.Click


Code:
If IsNumeric(tbxRandomCells.Text) = False Then
            MessageBox.Show("You must enter a number.", "Attention", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
            Return
        End If

        Dim MyArraycells(Me.lbxCellsArray.Items.Count - 1) As String

        Me.lbxCellsArray.Items.CopyTo(MyArraycells, 0)
        Dim myListcells As New List(Of String)
        myListcells.AddRange(MyArraycells)
        Dim rnd As New System.Random
        Dim randomnumber As Integer = 0
        Me.tbxRandomCells.Text = ""
        Dim count As Integer = 0

        If Integer.TryParse(tbxRandomCells.Text, count) Then
            If Int32.Parse(tbxRandomCells.Text) <= Int32.Parse(lblTotalCells.Text) Then
                Do While count <> 0
                    randomnumber = rnd.Next(0, myListcells.Count)
                    tbxRandomCells.Text &= myListcells(randomnumber) & vbCrLf & ""
                    myListcells.RemoveAt(randomnumber)
                    count -= 1
                Loop
            Else
                MessageBox.Show("Your random number is higher than" & vbCrLf & " the total number of cells.", "Attention", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End If
        End If
any ideas as to why? Only thing I can think of is that the listbox is data bound to an ms access DB. Would that cause the error?