Why kadhampa now not practise Dorje Shugden? That's because no this protector yet when Atisha founded Kadhampa. Now, HH Serkong Tritul Rinpoche (or now known as"Kadham Trichen Rinpoche" ) has recovered the teaching to Kadhampa. So, as a conclusion, although Kadhampa not practise Dorje Shugden but Kadham Lineage still recognize Dorje Shugden as a real Dharma Protector of Gelug...