return session.CreateQuery
   ("SELECT new LookupDTO(Id, Id) FROM Market").List<LookupDTO>();

NHibernate.QueryException: class not found: LookupDTO [SELECT new LookupDTO(Id, Id) FROM TransAlta.DealManagement.Domain.Market.Market]

[Serializable]
    public class LookupDTO
    {
        private string key;
        private string text;

        public LookupDTO()
        {
        }

        public LookupDTO(string key, string text)
        {
            this.key = key;
            this.text = text;
        }

        public string Key
        {
            get { return key; }
            set { key = value; }
        }

        public string Text
        {
            get { return text; }
            set { text = value; }
        }

        public override string ToString()
        {
            return text;
        }
    }
}

public class Market : DomainObject<string>
{
}

public class DomainObject<T> : IDomainObject
    {
        private T id;
        protected int version;
        protected DateTime createDate;
        protected DateTime lastModifiedDate;
        protected string createBy;
        protected string lastModifiedBy;


        public virtual void SetId(object o)
        {
            id = (T) o;
        }

        public void MarkModified()
        {
            LastModifiedDate = DateTime.Now;
            LastModifiedBy = Thread.CurrentPrincipal.Identity.Name;
        }

        public void MarkCreated()
        {
            Version = 1;
            CreateDate = DateTime.Now;
            CreateBy = Thread.CurrentPrincipal.Identity.Name;
            MarkModified();
        }

        public virtual T Id
        {
            get { return id; }
            set { SetId(value); }
        }

        public int Version
        {
            get { return version; }
            set { version = value; }
        }

        public DateTime CreateDate
        {
            get { return createDate; }
            set { createDate = value; }
        }

        public DateTime LastModifiedDate
        {
            get { return lastModifiedDate; }
            set { lastModifiedDate = value; }
        }

        public string CreateBy
        {
            get { return createBy; }
            set { createBy = value; }
        }

        public string LastModifiedBy
        {
            get { return lastModifiedBy; }
            set { lastModifiedBy = value; }
        }

        public override bool Equals(object obj)
        {
            if (this == obj) return true;
            DomainObject<T> _domainObject = obj as DomainObject<T>;
            if (_domainObject == null) return false;
            return Equals(id, _domainObject.id);
        }

        public override int GetHashCode()
        {
            return id.GetHashCode();
        }
    }

public interface IDomainObject
    {
        void SetId(object o);
        void MarkModified();
        void MarkCreated();

        int Version { get; set; }

        DateTime CreateDate { get; set; }

        DateTime LastModifiedDate { get; set; }

        string CreateBy { get; set; }

        string LastModifiedBy { get; set; }
    }

<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   assembly="TransAlta.DealManagement.Domain" namespace="TransAlta.DealManagement.Domain.Market">
 
  <class name="Market" table="mrktc" lazy="false" mutable="false" where="mrktc_active='1' AND mrktc_futopt IN ('I', 'P')">

    <id name="Id" column="mrktc_mkt" type="string" access="field.camelcase">
      <generator class="native" />
    </id>
 
  </class>
</hibernate-mapping>

NHibernate.Cfg.Configuration cfg = new NHibernate.Cfg.Configuration();

//This imports the class Fully.Qualified.Class so it can be queried in HQL as "MyClass".
cfg.CreateMappings().AddImport("Fully.Qualified.Class", "MyClass");

SessionFactory factory = cfg.Configure().BuildSessionFactory();

Configuration cfg = new Configuration();
cfg.Properties = DMSProperties;

DMS.DealManagement _dealManagement =
         new DMS.DealManagement();

cfg.AddAssembly(_dealManagement.GetType().Assembly);

cfg.CreateMappings().AddImport(
               "DealManagement.DTO.LookupDTO", "LookupDTO");

dmsSessionFactory = cfg.BuildSessionFactory();

return Session.CreateQuery("SELECT new LookupDTO(u.ZainetUserId,                     u.ProfileName) FROM UserProfile u").List<LookupDTO>();

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   assembly="xxx.DealManagement.Domain" namespace="xxx.DealManagement.Domain">
 
   <class name="UserProfile" table="User_Profile" lazy="false">     
      <id name="Id"  column="User_Profile_Id" access="field.camelcase" unsaved-value="0" type="Int32">
         <generator class="native"/>
      </id>
      <property name="ProfileName" column="Profile_Name" type="string" access="field.camelcase" not-null="true"/>
      <property name="ZainetUserId" column="Zainet_User_Id" type="string" not-null="false" access="field.camelcase"/>
      <property name="Version" column="Version" not-null="true" access="field.camelcase"/>
      <property name="CreateDate" column="Create_Date" not-null="true" access="field.camelcase"/>
      <property name="LastModifiedDate" column="Last_Modified_Date" not-null="true" access="field.camelcase"/>
      <property name="CreateBy" column="Create_By" not-null="true" access="field.camelcase"/>
      <property name="LastModifiedBy" column="Last_Modified_By" not-null="true" access="field.camelcase"/>

   </class>

</hibernate-mapping>

return Session.CreateQuery("SELECT new LookupDTO(u.ZainetUserId, u.ProfileName) FROM UserProfile u").List<LookupDTO>();