problem records insertion through asp.net

Hi all,


Here i am using checkbox list control and a button.In button click i wrote below code to insert values into a table in database.I write this code in loop because of I am using check box list control....

when i run my webform user can select single check box or multiple check boxes then when button click i want to insert those checked values into my table which has only one column

But when inserting from second record its showing below error....

The variable name '@counselor_name' has already been declared. Variable names must be unique within a query batch or stored procedure.

Here below is my code....

string st = "";

foreach (ListItem li in Chkcounselor.Items)
{
if (li.Selected)
{
st = li.Text.ToString();
SqlParameter counselorname = new SqlParameter("@counselor_name", SqlDbType.VarChar, 50);
counselorname.Value = st;
cmd.Parameters.Add(counselorname);
cmd.ExecuteNonQuery();

}
}

Please help me out....

thank you.