Try this:
protected void btnSearch_Click(object sender, EventArgs e)
{
sqlcon = new SqlConnection(strconn);
cmd = new SqlCommand("searchCriteriaSP", sqlcon);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter("@input", SqlDbType.VarChar)).Value = ddlSearch.SelectedValue;
da = new SqlDataAdapter(cmd);
da.Fill(ds);
if (ds.Tables[0].Rows.Count > 0)
{
GridView1.DataSource = ds;
GridView1.DataBind();
}
}
--Amit