I am stuck with this problems for a long time now.

Everything I try to do is insert a row in my DB if it's new information - if not update the existing one.

I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees...

private Models.databaseDataContext db = new Models.databaseDataContext();

internal void StoreInformations(IEnumerable<EntityType> iEnumerable)
{
 foreach (EntityType item in iEnumerable)
 {
  EntityType type = db.EntityType.Where(t => t.Room == iEnumerable.Room).FirstOrDefault();
  if (type == null)
  {
   db.EntityType.InsertOnSubmit(item);
  }
  else
  {
   cur.Date = item.Date;
   cur.LastUpdate = DateTime.Now();
   cur.End = item.End;
  }       
 }
}

internal void Save()
{
 db.SubmitChanges();
}