DataTable Filter mystery - asp.net

Question

could you please help me find the reason of the mystery I've found?
In the below code, I create a DataTable and filter it. When I use filter1, everything works as expected.
When I use filter2, everything works as expected only if the SubsectionAmount variable is less than 10.
As soon as I set SubsectionAmount=10, the dr2 array returns Nothing.
I can't find what is wrong. Here is the code:
Imports System.Data
Partial Class FilterTest
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Call FilterTable()
End Sub
Sub FilterTable()
Dim dtSubsections As New DataTable
Dim SectionID As Integer, SubsectionID As Integer
Dim SubsectionAmount As Integer
Dim filter1 As String, filter2 As String
Dim rowID As Integer
Dim dr1() As DataRow, dr2() As DataRow
With dtSubsections
.Columns.Add("Section")
.Columns.Add("Subsection")
.Columns.Add("FieldString")
SectionID = 1
SubsectionAmount = 10 '9
For SubsectionID = 1 To SubsectionAmount
.Rows.Add(SectionID, SubsectionID, "abcd" & CStr(SubsectionID))
Next SubsectionID
For rowID = 0 To .Rows.Count - 1
Response.Write(.Rows(rowID).Item(0).ToString & " " _
& .Rows(rowID).Item(1).ToString & " " _
& .Rows(rowID).Item(2).ToString & "<BR>")
Next
SubsectionID = 1
filter1 = "Section=" & SectionID & " AND " & "Subsection=" & SubsectionID
filter2 = "Section=" & SectionID & " AND " & "Subsection=" & SubsectionID + 1
dr1 = .Select(filter1)
dr2 = .Select(filter2)
Response.Write(dr1.Length & "<BR>")
Response.Write(dr2.Length & "<BR>")
If dr1.Length > 0 Then
Response.Write(dr1(0).Item("FieldString").ToString & "<BR>")
End If
If dr2.Length > 0 Then
Response.Write(dr2(0).Item("FieldString").ToString & "<BR>")
End If
End With
End Sub
End Class

Answer 1

The line
"Section=" & SectionID & " AND " & "Subsection=" & SubsectionID + 1
looks dodgy to me (?)
Consider this snippet of code:
var i = 2;
string j = "Hello " + i + 1;
when you print j you will get "Hello21" and not "Hello3". The + operator applied on a string will accept any object on the right-hand side and uses them by calling ToString() on the object, hence making your int effectively a string. Now, I assume that in VB.Net it is quite similar, which may not be what you want.
Update
Apparently VB.Net does things differently, so happily ignore...

Answer 2

change your column add statements to the following so it does the comparisons correctly.
.Columns.Add("Section", GetType(Integer))
.Columns.Add("Subsection", GetType(Integer))
.Columns.Add("FieldString")