Remember, that it's not case insensitive. In order to prevent any faults, i would convert everything to lowercase. I would try something like this:
Code:
Function StringBetween(ByVal s_String As String, ByVal s_Start As String, ByVal s_End As String) As String
If s_String.Contains(s_Start) AndAlso s_String.Contains(s_End) Then
StringBetween = Split(Split(s_String, s_Start)(1), s_End)(0)
Else
StringBetween = ""
End If
End Function
' .....
Dim res As String = StringBetween(source, "For This Useful Post:", "</table>")
If String.IsNullOrEmpty(InStr(res.ToLower, Uname.ToLower))) Then
MsgBox("You must press thanks")
End If
It might be very basic, but logically, it should work.