The Connection Property has not been initialized in asp.net.

" The Connection Property has not been initialized in asp.net." for below code...

private void InsertCommand()

    {

        try

        {

            //string str = "";

            String pfname = FileUpload1.FileName.ToString();

            String fname = System.IO.Path.GetFileNameWithoutExtension(pfname).ToString();

            String ext = System.IO.Path.GetExtension(pfname);

            fname = fname + DateTime.Now.ToString("dd-MM-yyyy-HH-mm-ss");

            fname = fname + ext;

            FileUpload1.SaveAs(Server.MapPath(@"./Images\\") + fname);

            String filepath = "~/Images/" + fname;

            sq = new SQLDataAccessHelper();

            SqlParameter[] param = new SqlParameter[10];

            param[0] = new SqlParameter("@username", SqlDbType.NVarChar);

            param[0].Value = Convert.ToString(txtUsername.Text);

            param[1] = new SqlParameter("@password", SqlDbType.NVarChar);

            param[1].Value = Convert.ToString(txtPassword.Text);

            param[2] = new SqlParameter("@employeename", SqlDbType.NVarChar);

            param[2].Value = Convert.ToString(txtEmployeename.Text);

            param[3] = new SqlParameter("@employeecode", SqlDbType.NVarChar);

            param[3].Value = Convert.ToString(txtEmployeecode.Text);

            param[4] = new SqlParameter("@email", SqlDbType.NVarChar);

            param[4].Value = Convert.ToString(txtEmail.Text);

            param[5] = new SqlParameter("@img", SqlDbType.Image);

            param[5].Value = filepath.ToString();

            param[6] = new SqlParameter("@contactno", SqlDbType.NVarChar);

            param[6].Value = Convert.ToString(txtContactnumber.Text);

            param[7] = new SqlParameter("@usertype", SqlDbType.NVarChar);

            param[7].Value = Convert.ToInt32(GetUserTypeId());

            param[8] = new SqlParameter("@groupcompanyid", SqlDbType.Int);

            param[8].Value = Convert.ToInt32(ddlGroupCompany.SelectedItem.Value);

            param[9] = new SqlParameter("@modifiedby", SqlDbType.Int);

            param[9].Value = DBNull.Value;

            ds = new DataSet();

            ds = sq.ExecuteDataSet("usp_InsertUsers", param);

            if ((ds != null) && (ds.Tables.Count != 0) && (ds.Tables[0].Rows.Count != 0) && (ds.Tables[0].Rows[0]["Message"].ToString().ToLower() == "yes"))

            {

                lblMsg.Text = "Data submitted successfully!";

                lblMsg.ForeColor = System.Drawing.Color.Green;

                ResetCommand();

            }

            else

            {

                lblMsg.Text = "Error while submitting data!";

                lblMsg.ForeColor = System.Drawing.Color.Red;

                ResetCommand();

            }

        }

        catch                                                                                            //  error -  the connection property has not been initialized//

        {

            lblMsg.Text = "Error while submitting data!";

            lblMsg.ForeColor = System.Drawing.Color.Red;             

        }

    }