How to destroy target created by calling dataset.Load()

I want to dynamically load and destroy datasets. The load and activate is ok.  Even deactivate is ok.  However, when I try to destroy the dataset,  it generates errors as

Could not destroy trackable with id 1

Could not destroy trackable with id 2

code :

tracker.Stop ();

tracker.DeactivateDataSet (m_Dataset);

tracker.DestroyDataSet (m_Dataset, true);