Vb.net calculation problem.

How am i supposed to set this up? I've tried using what I've got but it won't calculate what I need to properly. Breakdown:
I have a program were I'm supposed to calculate books read and award points
based on a certain amount of books read by the reader. In the place of some numbers I used constants.
1-3 books = 10pts ea.
next 3 books = 15pts ea.
6 or more = 20pts ea.

'Declared Constants
    Const BOOKS_READ1Integer As Integer = 10
    Const BOOKS_READ2Integer As Integer = 15
    Const BOOKS_READ3Integer As Integer = 20
    Const MAX_BOOKS_ALLOWED_READInteger As Integer = 10000
 
    'Declared Variables
    Dim totalPointsDecimal, booksReadInteger, bookPoints, _
    customerCountInteger, numberBooksReadInteger, totalBooksRead, _
    numbooksRead, average, booksRead As Integer
 
 
    Private Function calculatePointsDataType(ByVal bookValue As String) As Integer
        Dim bookPoints As Integer
 
        Try
            Dim numberBooksRead As Integer = Integer.Parse(numBooksReadTextBox.Text)
 
            If numberBooksRead <= 1 And 3 Then
                bookPoints = numberBooksRead * BOOKS_READ1Integer
            ElseIf numberBooksRead < 3 And = 6 Then
                bookPoints = 3 * BOOKS_READ1Integer + numberBooksRead - 3 * BOOKS_READ2Integer
            ElseIf numberBooksRead >= 6 And MAX_BOOKS_ALLOWED_READInteger Then
                bookPoints = (3 * BOOKS_READ2Integer) + (3 * BOOKS_READ2Integer) + (numberBooksRead - 6) * (BOOKS_READ3Integer)
 
            End If
        Catch ex As Exception
        End Try
 
        Return bookPoints
    End Function

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