SqlCommand.StatementCompleted Event - How To Use In ASP

Hi, I've come from desktop to web (say no more?)

I'd like to fire a sqlCommand.StatementCompleted event in ASP.NET & use the sender argument to retrieve the output of a stored proc.

The command is in a button event. The event handler += is also set up in the same button event. Naturally the event handler proc is separate as its own procedure

In the event handling procedure, I cast the sender arg. to an SQLCommand object & try to extract the value of the output parameter.

When I try to do this I get a "No reference set to object" error raised in . Is this because there was a post back after the command completed & the Command object lost its state? If so, what would be the best way to retain the parameters value? Using session state or Profile?

Any help would be greatly appreciated

below is cut down code as to what I'm doing:protected void Button1_Click(object sender, EventArgs e)
{
SqlCommand cmd = new SqlCommand();
cmd.StatementCompleted += new StatementCompletedEventHandler(c_StatementCompleted); cn.Open();
cmd.ExecuteNonQuery();
cn.Close();
}
void c_StatementCompleted(object sender, StatementCompletedEventArgs e)
{
// get an error here
string result = ((SqlCommand)sender).Parameters["returnPrm"].Value.ToString();
}