Displaying book titles

So I have a form with a menu bar and a listbox. On the menu bar is the Display option with 3 choices; all, fiction, or nonfiction. The textfile has book titles, author, category (fic"F" or nonfic"N"), stock, price, in that order. When the user clicks on "Display" "all", I want all the titles to display in the listbox. If they click on "Nonfic", just the nonfic titles, and same with "fiction". This is my code so far:

Private Sub menuDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles menuDisplay.Click

Dim books() As String = IO.File.ReadAllLines("Books.txt")
Dim data() As String
Dim allBooksTitle, allNonFicTitle, allFicTitle As String

For i As Integer = 0 To books.Count - 1
data = books(i).Split(","c)
allBooksTitle = data(2)
If data(2).Trim = "N" Then
allNonFicTitle = data(0)
ElseIf data(2).Trim = "F" Then
allFicTitle = data(0)
End If
Next

' show result
If menuDisplayAll.Checked Then
menuDisplayFic.Checked = False
menuDisplayNonFic.Checked = False
lstBox.Items.Clear()
lstBox.Items.Add(allBooksTitle)
ElseIf menuDisplayFic.Checked Then
menuDisplayNonFic.Checked = False
menuDisplayAll.Checked = False
lstBox.Items.Clear()
lstBox.Items.Add(allFicTitle)
ElseIf menuDisplayNonFic.Checked Then
menuDisplayFic.Checked = False
menuDisplayAll.Checked = False
lstBox.Items.Clear()
lstBox.Items.Add(allNonFicTitle)
End If
End Sub

Yet, Every time I debug it, to actually get the titles to show up in the listbox after i check one option, I have to click the values button again. Also, it only shows one book title or both the nonfiction and the fiction, and then for all book it only shows "N". I don't know what I am doing wrong. Any help would be appreciated!

Here is a conceptual example of working with your data (my source I am sure is slightly different than yours yet you can adapt). No UI controls are used, should be easy for you to work out.

Code:

---

Dim dt As New DataTable

dt.Columns.Add(New DataColumn With {.ColumnName = "Title", .DataType = GetType(String)})
dt.Columns.Add(New DataColumn With {.ColumnName = "Author", .DataType = GetType(String)})
dt.Columns.Add(New DataColumn With {.ColumnName = "Category", .DataType = GetType(String)})
dt.Columns.Add(New DataColumn With {.ColumnName = "Stock", .DataType = GetType(Int32)})
dt.Columns.Add(New DataColumn With {.ColumnName = "Price", .DataType = GetType(Decimal)})

Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("Books.txt")
    MyReader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
    MyReader.Delimiters = New String() {","}
    Dim Row As String()
    While Not MyReader.EndOfData
        Try
            Row = MyReader.ReadFields()
            dt.Rows.Add(New Object() _
                {
                    Row(0),
                    Row(1),
                    IIf(Row(2) = "F", "Fiction", "Non-Fiction").ToString,
                    CInt(Row(3)),
                    CDec(Row(4))
                }
            )
        Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
            Console.WriteLine(ex.Message)
        End Try
    End While
End Using


Dim dvFiction As DataView = dt.DefaultView
dvFiction.RowFilter = "Category = 'Fiction'"
For Each row As DataRowView In dvFiction
    Console.WriteLine(String.Join(",", row.Row.ItemArray))
Next
Console.WriteLine()
Dim dvNonFiction As DataView = dt.DefaultView
dvFiction.RowFilter = "Category = 'Non-Fiction'"
For Each row As DataRowView In dvNonFiction
    Console.WriteLine(String.Join(",", row.Row.ItemArray))
Next

---

File Books.txt

Code:

---

Title1,Bob Smith,F,10,12.99
Title2,Jane Anderson,N,2,3.99
Title3,Serge Abiteboul,F,5,10.78
Title4,Dan Suciu,N,3,23.87

---

Results

Code:

---

Title1,Bob Smith,Fiction,10,12.99
Title3,Serge Abiteboul,Fiction,5,10.78

Title2,Jane Anderson,Non-Fiction,2,3.99
Title4,Dan Suciu,Non-Fiction,3,23.87

---