VB specific line of text to bold in a multi-line TextBox - vb.net

Question

I'm writing a reminder program in vb.net that reads a text file and displays dated entries from today to 14 days from today. I want entries for today's date to be in bold. If it makes any difference I'm using a TextBox instead of Rich TextBox This is what I've tried:
Public Sub getReadFile()
' rtfRead is the name of the TextBox
rtfRead.Text = Nothing
' Today, the first read line date
Dim startDate As Date = Date.Now()
' First dated line to read
Dim todayDate As String = (GetDateInMyFormat(startDate))
' The last read line date
Dim endDate As String = (GetDateInMyFormat(DateAdd("d", 14, startDate)))
' The first 4 characters of a line. Are the 4 charcters numbers, i.e. yyyy
Dim lineStart As Object
' The date at the beginnig of a an entry
Dim lineDate As String = Nothing
' Are the first 4 charcters of a line numeric = True
Dim isNum As Boolean = False
' TM_Notes.txt
Dim readFile As String = Nothing
Dim oldFont As Font = rtfRead.Font
Dim boldFont As Font = New Font(rtfRead.Font, FontStyle.Bold)
Try
' Create an instance of StreamReader to read from a file.
' The using statement also closes the StreamReader.
Using sr As New StreamReader("TM_Notes.txt")
Dim lineRead As String
' Read and display lines from the file until the end of
' the file is reached.
Do
lineRead = sr.ReadLine()
lineStart = Mid(lineRead, 1, 4)
isNum = IsNumeric(lineStart)
If isNum = True Then
lineDate = GetDateInMyFormat(Mid(lineRead, 1, 10))
End If
If lineDate = todayDate Then
rtfRead.Font = boldFont
Else
rtfRead.Font = oldFont
End If
If Not (lineRead Is Nothing) And isNum = False And lineDate <= endDate Then
readFile = readFile + lineRead & vbCrLf
ElseIf lineDate >= todayDate And lineDate <= endDate Then
readFile = readFile + lineRead & vbCrLf
End If
Loop Until lineRead Is Nothing
End Using
rtfRead.Text = readFile
Catch ex As Exception
' Let the user know what went wrong.
Console.WriteLine("The file could not be read:")
Console.WriteLine(ex.Message)
End Try
End Sub
I don't get any errors but today's date isn't in bold.
It today is 02-11 then the Test string line should be bold.
2014-02-11: Test string
2014-02-12: Test string 2
UPDATE
I've changed to a Rich TextBox and updated my code sample to to reflect my code changes. I'm still not getting Bold

Answer 1

Here's the function... You pass the text you want to find and the format (bold or italic - 1 or 2). This works really good; you can also expand this to add color if you choose. I hope you find this useful, happy coding!
'Pass in a 1 or 2; one is bold the other is italic'
Private Function FormatText(ByVal TextToFormat As String, ByVal TextFormat As Integer)
Dim count As New List(Of Integer)()
For i As Integer = 0 To rText.Text.Length - 1
If rText.Text.IndexOf(TextToFormat, i) <> -1 Then
'If the word is found add the index to the list
count.Add(rText.Text.IndexOf(TextToFormat, i))
End If
Next
Try
For i As Integer = 0 To count.Count - 1
rText.[Select](count(i), TextToFormat.Length)
Select Case TextFormat
Case 1
rText.SelectionFont = New Font(rText.Font.FontFamily, rText.Font.Size, FontStyle.Bold)
Case 2
rText.SelectionFont = New Font(rText.Font.FontFamily, rText.Font.Size, FontStyle.Italic)
End Select
count.RemoveAt(i)
Next
Catch
End Try
Return Nothing
End Function