problem with Creation of customer method

public ClientTopNet CreationClient(int ID_CLIENT, string LOGIN_CREATION, DateTime DATE_CREATION, string LOGIN_MODIFICATION, DateTime DATE_MODIFICATION, int TYPE_CLIENT, int CIVILITE, string NOM, string PRENOM, string FONCTION, string RS, string CIN, string ADRESSE, string VILLE, int CP, int GOUVERN, string TEL, string GSM, string FAX, string EMAIL, int CD_ORIGINE, string OBSERV, int EXONERE, int EXOTIMBRE, int SECTEUR_ACT, int VIP, string CHARGECOMPTE, string CHARGECOMPTE_RD, int CATEGORIE, string REGISTRE, int METHOD_ENVOI_FACT, int PERSONNEL, string REF_CLIENTCRM)
        {    
           System.Data.OleDb.OleDbConnection conn = new     System.Data.OleDb.OleDbConnection();
            
           conn.ConnectionString = @"Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;User ID=topnet;Initial Catalog=TopnetBase;Data Source=SWEET-4B6F892B4\SQLEXPRESS";
           //Clients oClients = new Clients();
           ClientTopNet oClient = new ClientTopNet();
           try
           {
               conn.Open();

               int r;

               string req = "INSERT INTO client ( ID_CLIENT,LOGIN_CREATION , DATE_CREATION,LOGIN_MODIFICATION ,DATE_MODIFICATION,TYPE_CLIENT, CIVILITE,NOM,PRENOM,FONCTION,RS,CIN,ADRESSE,VILLE, CP, GOUVERN ,TEL,GSM,FAX,EMAIL,CD_ORIGINE,OBSERV,EXONERE,EXOTIMBRE,SECTEUR_ACT ,VIP, CHARGECOMPTE,CHARGECOMPTE_RD ,CATEGORIE,REGISTRE,METHOD_ENVOI_FACT,PERSONNEL,REF_CLIENTCRM )VALUES ('" + ID_CLIENT + "','" + LOGIN_CREATION + "','" + DATE_CREATION + "','" + LOGIN_MODIFICATION + "','" + DATE_MODIFICATION + "','" + TYPE_CLIENT + "','" + CIVILITE + "','" + NOM + "','" + PRENOM + "','" + FONCTION + "','" + RS + "','" + CIN + "','" + ADRESSE + "','" + VILLE + "','" + CP + "','" + GOUVERN + "','" + TEL + "','" + GSM + "','" + FAX + "','" + EMAIL + "','" + CD_ORIGINE + "','" + OBSERV + "','" + EXONERE + "','" + EXOTIMBRE + "','" + SECTEUR_ACT + "','" + VIP + "','" + CHARGECOMPTE + "','" + CHARGECOMPTE_RD + "','" + CATEGORIE + "','" + REGISTRE + "','" + METHOD_ENVOI_FACT + "','" + PERSONNEL + "','" + REF_CLIENTCRM + "')";
               System.Data.OleDb.OleDbCommand command = new System.Data.OleDb.OleDbCommand(req, conn);

               r = command.ExecuteNonQuery();
               conn.Close();
               return oClient;
           }
           catch (System.Data.SqlClient.SqlException ex)
           {

               string msg = "Insert Error:";

               msg += ex.Message;

               throw new Exception(msg);

           }