VS 2010 DirectCast used to work and now it doesn't

Private Sub btnMatchLetters_Click(sender As System.Object, e As System.EventArgs) Handles btnMatchLetters.Click
        Dim Letters(9) As String
        Dim WordLength As Integer = 10
        'clear the listbox ready for a new list
        ListBox1.Items.Clear()
        'work backwards until find first highlighted textbox which indicates length of word
        'DirectCast here allows us to refer to each textbox by its number
        For CtrlPtr As Integer = 10 To 1 Step -1
            If DirectCast(Me.Controls("TextBox" & CtrlPtr.ToString), TextBox).BackColor = Color.DarkCyan Then
                'found length so get out
                WordLength = CtrlPtr
                Exit For
            End If
        Next
        'copy the letters to an array so we can check them
        For CtrlPtr = 10 To 1 Step -1
            Letters(CtrlPtr - 1) = DirectCast(Me.Controls("TextBox" & CtrlPtr.ToString), TextBox).Text().ToLower
        Next
 
        For Each word In Dict
            'ProgressBar1.PerformStep()
            Dim MatchLetters As Boolean = True      'set flag to true before entering the routine. It will  be set to false on no match
            If word.Length = WordLength Then        'for speed only check words of the correct length
                For Letter As Integer = 0 To word.Length - 1
                    'check each letter in turn
                    'ignore blank spaces
                    'if letter does not match, set flag to false
                    If Letters(Letter) <> "" AndAlso Letters(Letter) <> word.Substring(Letter, 1) Then MatchLetters = False
                Next
                'when word is checked, if the flag is still true, add it to the listbox
                If MatchLetters = True Then
                    ListBox1.Items.Add(word)
                End If
            End If
        Next
        lblMatches.Text = ListBox1.Items.Count.ToString & " Matches"
    End Sub

Private Sub btnClear_Click(sender As System.Object, e As System.EventArgs) Handles btnClear.Click
        For CtrlPtr = 10 To 1 Step -1
            'directcast allows us to reference the textboxes by their number
            DirectCast(Me.Controls("TextBox" & CtrlPtr.ToString), TextBox).Clear()
            DirectCast(Me.Controls("TextBox" & CtrlPtr.ToString), TextBox).BackColor = Control.DefaultBackColor
        Next
    End Sub

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        'the files are called "A Words" "B Words" etc. CHR65 to 90 represent capital A to Z
        '        For LetterRef As Integer = 65 To 90
        'create the filename
        ' MyFile = Chr(LetterRef) & " Words.csv"
        MyFile = "dictionary.txt"
        'read it
        Dim Words() As String = File.ReadAllLines(MyFile)
        Dim f As Integer = 0
        For f = 1 To Words.Length - 1
            'add to the final list
            Dict.Add(Words(f))
        Next
        NoOfWords = f           'save the number of words to be used later by the progressbar
        ProgressBar1.Maximum = CInt(NoOfWords)
        ProgressBar1.Minimum = 0
 
        '        Next