使用了SqlHelper，如何让它回滚,如何取回返回值

SqlConnection CS;
CS = new SqlConnection(m_strConnectionString);

SqlTransaction DBTransaction = null;
string p_strReturnMessage = "";
int p_intOutPut = 0;

try
{
#region Populate Parameters
System.Data.SqlClient.SqlParameter[] arParams = new System.Data.SqlClient.SqlParameter[4];

arParams[0] = new System.Data.SqlClient.SqlParameter("@intOrganizeID", System.Data.SqlDbType.Int);
arParams[1] = new System.Data.SqlClient.SqlParameter("@strMacAddress", System.Data.SqlDbType.VarChar, 256);
arParams[2] = new System.Data.SqlClient.SqlParameter("@strMacCheck", System.Data.SqlDbType.VarChar, 256);
arParams[3] = new System.Data.SqlClient.SqlParameter("@intOutPut", System.Data.SqlDbType.Int);

arParams[3].Direction = System.Data.ParameterDirection.Output;

arParams[0].Value = 1;
arParams[1].Value = "111";
arParams[2].Value = "111";
arParams[3].Value = p_intOutPut;
#endregion

#region Execute SQL
CS.Open();
DBTransaction = CS.BeginTransaction();
SqlHelper.ExecuteNonQuery(DBTransaction, CommandType.StoredProcedure, "pro_T_Accredit_Create", arParams);

p_intOutPut = Convert.ToInt32(arParams[3].Value.ToString());
#endregion

#region Check Result
if(p_intOutPut < 0)
{
DBTransaction.Rollback(); //--回退事务
}
else
{
DBTransaction.Commit(); //--提交事务
}
#endregion
}
catch(System.NullReferenceException NullEx)
{
DBTransaction.Rollback(); //--回退事务
}
catch(Exception ex)
{
DBTransaction.Rollback(); //--回退事务
}