Acess dataset between 2 Windows Form

Dear all
If I have 2 form, 1 call form1 and the other call form2.
I create a connection in form1:


CLASS FORM1
PUBLIC DS As DATASET

Dim connstr As String = "DSN=TEST"
Dim cn As New OdbcConnection(connstr)
Dim DA1 As New OdbcDataAdapter("SELECT * FROM A ", cn)

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

cn.Open()
odbcadapter1.Fill(DS, "A")

I can successfully access DS in form1, but when I try to access DS in form2, it said" object reference not set to instance of object". It seem that it treat it as a new variable. I try this in form2:

Dim zds As DataSet

zds = form1.ds
messagebox.show(zds.tables("A").Rows.count)

But still not work. Anyone can told me how to access it from anothe table? Thank you very much.

Just pass the dataset to Form2.

Thank you for your reply.
But How?
Thank you

in Form1 :

VB Code:

Public ds As New DataSet()
'/// make a public reference to ds ^^^
'///////////////////////////////////////////////
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim frm2 As New Form2()
    AddOwnedForm(frm2) '/// add it as owned by this form.
    frm2.Show()
End Sub

in Form2 :

VB Code:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim frmMain As Form1 = Owner
    Dim zds As DataSet = frmMain.ds
    MessageBox.Show(zds.DataSetName)
End Sub

Thank you for your reply. I have one question. Once I declar a public variable :

public ds as new dataset()

it doesnot mean I can access it everywhere? Or I can just access the variable, but not the value of the ds.....I quite confuse.
Now, It seem that I can use ds in form2 but I can not access the "value" in form2.

Another one told me a method is declare the dataset in a modules. What is the differece between declare a varibale as public and declare it in a modules. As I know, it looks like equal since both method can access the variable everywhere. Sorry for my long question. Sorry and Thank you for your help.

here's a quick example , using oledb to open an access app
in Form1 :

VB Code:

Imports System.Data
 
Public ds As New DataSet()
Private frm2 As New Form2()
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    AddOwnedForm(frm2)
    frm2.Show()
 
End Sub

in Form2 :

VB Code:

Imports System.Data.OleDb
 
    Private frmMain As Form1
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim constring As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyDb.mdb"
        frmMain = Owner '/// owner form.
 
        OpenAccess(constring)
    End Sub
 
    Public Function OpenAccess(ByVal strConnection As String, Optional ByVal strCommand As String = "SELECT * FROM Table1")
        Dim objCon As New OleDbConnection(strConnection)
        Try
            objCon.Open()
            Dim objCom As New OleDbCommand(strCommand, objCon)
            Dim objAdapt As New OleDbDataAdapter(objCom)
 
            objAdapt.Fill(frmMain.ds, "Table1")
            DataGrid1.DataSource = frmMain.ds.Tables("Table1")
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
            objCon.Close()
        End Try
 
    End Function