Nested Datareader in c#.net

[Brinda Arumugam]

Hi,

I'm New to Mysql Database. i have trouble in accessing multi datareader with in single connection.

error occur:
There is already an open DataReader associated with this Connection which must be closed first.

This is my coding
MySqlCommand cmd = new MySqlCommand("select DISTINCT IBillNo,Advv,NetTotal,CName,CPhoneNo,EID from InvoiceDetails where DStatus='D'", con);
MySqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
Double NetA = 0, Adv = 0;
if (dr[2] == DBNull.Value || dr[2].ToString() == null)
{
NetA = 0;
}
else
{
NetA = Convert.ToDouble(dr[2].ToString());
}

if (dr[1] == DBNull.Value || dr[1].ToString() == null)
{
Adv = 0;
}
else
{
Adv = Convert.ToDouble(dr[1].ToString());
}
Double Pnt = 0;
MySqlCommand pay = new MySqlCommand("select * from PaymentDetails where IBillNo='" + dr[0].ToString() + "'", con);
MySqlDataReader drpay = pay.ExecuteReader();
while (drpay.Read())
{
if (drpay["Payment"] == DBNull.Value || drpay["Payment"].ToString() == null)
{
Pnt = 0;
}
else
{
Pnt = Pnt + Convert.ToDouble(drpay["Payment"].ToString());
}
}
drpay.Dispose();
pay.Dispose();

if ((NetA - (Adv + Pnt)) > 0)
{
if (dr["EID"] == DBNull.Value || dr["EID"].ToString() == null || dr["EID"].ToString() == "")
{
int x = PaymentLoop.Rows.Add();
PaymentLoop.Rows[x].Cells[0].Value = dr[0].ToString();
PaymentLoop.Rows[x].Cells[1].Value = dr[3].ToString() + " -- " + dr[4].ToString();
PaymentLoop.Rows[x].Cells[2].Value = NetA.ToString();
PaymentLoop.Rows[x].Cells[3].Value = (NetA - (Adv + Pnt)).ToString();
}
}
}
cmd.Dispose(); dr.Dispose();
PaymentLoop.ClearSelection();


Let me know the solution...