Problem with PrimaryKey TGuid

I have a table with TGuid as primary key.
If I store a dataset, the Guid in database is random
If I read the dataset, I don't find it.

Here are the entities



  [Entity]
  [Table('t_ced_app')]
  [Id('FAppID', TIdGenerator.None)]
  TApp = class
  private
    [Column('app_id', [TColumnProp.Required])]
    FAppID: TGuid;
    ...
  public
    property AppID: TGuid read FAppID write FAppID;
    ...


and here is the code for finding und new insert



var
  LApp : TApp;
begin
  LApp := dmDatabase.DBSession.objManager.Find<TApp>(AppID);
  if LApp <> nil then
    dmDatabase.DBSession.objManager.Remove(LApp);


  LApp := TApp.Create;
  LApp.AppID   := AppID;
  LApp.RegTime := Now;
  LApp.Name    := AppName;
  LApp.User    := Username;
  dmDatabase.DBSession.objManager.Save(LApp);

Sorry, the error is at another place.
I have written "TGuid.create(string)" instead of "StringToGuid(string)"

I searched for a long time, but had to write it first to recognize the error. SORRY!!