C# - Nhibernate - Getting Exception Executing SQL Query?

I am excuting SQL Query using Nhibernate, here is my code

public ArrayList getDocumentsForApproval(string ReleaseId)
{
string query = string.Format("SELECT distinct doc.Id, doc.Name as Doc, doc.url as url, suser.Name as Author, ds.name, CONVERT(VARCHAR(11), doc.DateEntered, 101) as DateEntered FROM dbo.Documents doc INNER JOIN DevelopmentSteps ds ON doc.TypeId = ds.Id INNER JOIN DocumentTrackingItems dti ON doc.Id = dti.DocumentId INNER JOIN TrackingItems ti ON dti.ItemStepId = ti.Id INNER JOIN dbo.Releases rl ON ti.ReleaseId = rl.BugTrackerName left outer join (select * from users) as suser on doc.AuthorUserid = suser.Id WHERE doc.DateEntered IS NOT NULL AND doc.DateApproved IS NULL AND rl.ID = '{0}'", ReleaseId);
ISession session = NHibernateHelper.GetCurrentSession();
ArrayList document =(ArrayList) session.CreateSQLQuery(query).List();
return document;
}

Exception Details:

NHibernate.QueryException: Return types of SQL query were not specified [SELECT distinct doc.Id, doc.Name as Doc, doc.url as url, suser.Name as Author, ds.name, CONVERT(VARCHAR(11), doc.DateEntered, 101)