Quick question!

[rams23]

This is a program where you can enter 2 first letters of a state in the masked textbox, click the search button, and see the full name of the state displayed inside a regular textbox.
I am having a little problem at the end getting txtOutput.Text to produce the name of the state selected. Here is what i have:

Private Sub btnSearch_Click(sender As System.Object, e As System.EventArgs) Handles btnSearch.Click
        Dim first, last, middle As Integer
        Dim flag As Boolean = False
        first = 0
        last = lstStates.Items.Count - 1
        Dim letters As String = mtbFirstTwoLetters.Text.ToUpper
        While first <= last
            middle = CInt((first + last) / 2)
            Dim state As String =
                CStr(lstStates.Items.Item(middle)).ToUpper
            If state.StartsWith(letters) Then
                flag = True
                Exit While
            Else
                Dim st As String = state.Substring(0, 2)
                If letters > st Then
                    first = middle + 1
                Else
                    last = middle - 1
                End If
            End If
        End While
        If flag Then
            txtOutput.Text = 
        Else
            txtOutput.Text = "The State Is Not Found"
        End If
    End Sub
End Class