hi
im working on windows application.vb.net
In this Application iam using two forms
one is invoice form
other one is search form
first form one find button used to i will click button search form showme,
my search form i am using datagridview datagridview some field product id,product name,price list i will double click product id select row value display first form text Box 's that is invoice form

first form invoice find button code

Dim ProductSearch As New ProductSearch
' ProductSearch.MdiParent = Me
ProductSearch.Show()

this is my coding for search form
datagridview_doubleclick write
con.Open()
Dim str As String
Dim msg As String
msg = ""
Dim pid As Integer
Dim inv As New InvoiceEntry

inv.Show()
str = "Select * From ProductClas where Product_CID=" + DataGridView1.Rows(e.RowIndex).Cells(0).Value.ToString + ""
cmd = New OleDbCommand(str, con)
dr = cmd.ExecuteReader
If Trim(msg) = "" Then
If dr.Read Then
pid = dr.Item("Product_CID")
TextBox1.Text = pid
inv.Txt_InvProductCode.Text = dr.Item("Product_CID")
inv.Txt_InvProductname.Text = dr.Item("Product_CName")
inv.Txt_InvProductPrice.Text = dr.Item("Unit_Price")
End If

End If
con.Close()

data will be retreiveing correctly. but it is opening in a new invoice form each time but already old invoice form is opened , the new invoice form should not be opened and data should be retrieved in old the invoice form which is already opened
how should i do this