backgroundworker retrieve data from database. timeout expired

Question

This is the first time I use background worker. I want to retrieve data around 20.000 rows, save it on dataadapter and showing in on a datagridview

it seems running but then message Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding comes up.

What I have done is put : Connect Timeout=90000 on the connection string and da.SelectCommand.CommandTimeout = 2000000, which doesn't seems to have a better end result by make adding few extra zeroes. :( Here is what I have done. What should I do to make it works. thank you

Dim da As MySqlDataAdapter
Dim resultDataTable As DataTable
Dim queryString As String

Private Sub BTNrefresh_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BTNrefresh.Click
    queryString =" LONG QUERY "
    bw.RunWorkerAsync()
End Sub

Private Sub bw_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bw.DoWork
    MethodGlobal.mySqlCon.Open()

    da = New MySqlDataAdapter(queryString, MethodGlobal.mySqlCon)
    myDataTable = New DataTable

    da.Fill(myDataTable)
    da.SelectCommand.CommandTimeout = 2000000
    Me.DGVtest.DataSource = resultDataTable 
End Sub

Private Sub backgroundworker_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    MethodGlobal.NewMysqlConnection("connection")
End Sub