Binding data in my DatagridView in C# using Nhibernate -

i want add data datagridview. dniveau , dcycle are:

class dniveau : idniveau {     dparams dparams;     itransaction tx;     isession mysession;      public niveau oncreate(niveau niveau)     {          niveau nivo = null;          dparams = new dparams();          mysession = dparams.isession();           tx = mysession.begintransaction();          mysession.save(niveau);          nivo = mysession.get<niveau>(niveau._idniveau);          tx.commit();           mysession.close();          return null;     }      public list<niveau> getall()     {                      list<niveau> lniveau;          dparams = new dparams();          mysession = dparams.isession();                       tx = mysession.begintransaction();          tx.commit();           lniveau = (list<niveau>)mysession.createcriteria<niveau>().list<niveau>();          mysession.close();           return lniveau;     } } 

dcycle.cs

class dcycle : idcycle {     protected static readonly ilog _log = logmanager.getlogger(typeof(program));      dparams dparams;     itransaction tx;     isession mysession;      public cycle oncreat(cycle cycle)     {         dparams = new dparams();         mysession = dparams.isession();          tx = mysession.begintransaction();         mysession.save(cycle);         tx.commit();          mysession.close();         return null;     }      public list<cycle> getall()     {          list<cycle> lclis;          dparams = new dparams();          mysession = dparams.isession();          tx = mysession.begintransaction();          lclis = (list<cycle>)mysession.createcriteria<cycle>().list<cycle>();          tx.commit();          //  mysession.close();          return lclis;     } } 

this objects niveau , cycle

public class niveau {     public virtual int _idniveau { get; set; }     public virtual string _designation { get; set; }     public virtual cycle _cycle { get; set; }      public override string tostring()     {         return string.format("_idniveau: {0}, _designation: {1}, _cycle:  {2}");     } }  public class cycle {     public virtual  int _idcycle { get; set; }     public virtual  string _designation { get; set; }      public virtual etablissement etablissement { get; set; } } 

and hibernate mapping file both

<?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"  namespace="openskull.entites"   assembly="openskull"> <class name="cycle" table="cycle"> <id name="_idcycle" column="idcycle"> <generator class="native"/> </id>  <property name="_designation" column="designation"/> <many-to-one name="etablissement" class="etablissement"  column="idetablissement" cascade="save-update"/> </class> </hibernate-mapping>   <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"  namespace="openskull.entites" assembly="openskull"> <class name="niveau" table="niveau"> <id name="_idniveau" column="idniveau"> <generator class="native"/> </id> <property name="_designation" column="designation"/> <many-to-one name="_cycle" class="cycle" column="idcycle" cascade="save- update"/> </class> </hibernate-mapping> 

and code use add data

if (lnivo != null && icycl != null) {     cursor.current = cursors.waitcursor;     //  datagridview.datasource = lnivo;     niveaubindingsource4.datasource = lnivo;     cyclebindingsource3.datasource = icycl.getall();                     cursor.current = cursors.default; 

when compile ok when click form appears error appears:

the following exception occurred in datagridview: system.formatexception: datagridviewcomboboxcell value not valid.

to replace default dialog please handle dataerror event.

and after error:

enter image description here

thanks blocked. new language