NHibernate.MappingException. Why cant NHibernate not determine type -

i have problem when try make fk reference. mappingexception

nhibernate.mappingexception: not determine type for: jps.internal.domain.model.user, > jpscore, version=1.0.0.0, culture=neutral, publickeytoken=null, columns: nhibernate.mapping.column(deptorssoid)

my entities looks this

    public class payexagreement : entitybase {      public int                     subscriptionnumber           { get;  set; }       public user                    deptorsso                    { get;  set; }     public string                  payexagreementref            { get;  set; }     public string                  payexmaskednumber            { get;  set; }     public string                  payexpaymentmethod           { get;  set; }     public datetime                payexpaymentmethodexpiredate { get;  set; }     public ilist<subscriptionorder> subscriptionorderlist        { get;  set; }  }  public class user : entitybase {       public guid                 ssoid                          { get; set; }     public string               ssoemail                       { get; set; }     public contact              contact                        { get; set; }  }                                                         

and mappingfile payexagreement

 public class payexagreementmap : entitybasemap<payexagreement> {      public payexagreementmap()     {          map(x => x.payexagreementref).column("payexagreementref").customtype("ansistring").length(50).not.nullable();         map(x => x.payexpaymentmethod).column("payexpaymentmethod").customtype("ansistring").length(50).not.nullable();         map(x => x.payexmaskednumber).column("payexmaskednumber").customtype("ansistring").length(50).not.nullable();         map(x => x.payexpaymentmethodexpiredate).column("payexpaymentmethodexpiredate").not.nullable();           hasmany(x => x.subscriptionorderlist).keycolumn("payexagreementref").propertyref("payexagreementref").asbag().not.lazyload().cascade.none();         references(x => x.deptorsso).column("deptorssoid").propertyref("ssoid").not.nullable().cascade.none(); 

and tablesql

create table [dbo].[payexagreement] ( [id]                               int                  not null identity(1,1), [deptorssoid]                      uniqueidentifier     not null,  [payexagreementref]                varchar(50)          not null, [payexmaskednumber]                varchar(50)          not null, [payexpaymentmethod]               varchar(50)          not null, [payexpaymentmethodexpiredate]     datetime             not null,     constraint [pk_payexagreement]                   primary key clustered ([id]                desc),  constraint [fk_payexagreement_user]              foreign key           ([deptorssoid])      references [user]([ssoid])  on delete no action on update no action); 

i can't figure out why nhibernate doesn't recognize type (guid) of column. think problem when try make foreign key reference, solution escapes me.

edit!! here mapping user class

public class usermap : entitybasemap<user> {     public usermap()     {         map(x => x.ssoemail).column("email").customtype("ansistring").not.nullable();         map(x => x.ssoid);          references(x => x.contact).column("contactid").cascade.saveupdate();      } }