Since, you did not post any source code I'm guessing you're not inflating your view from an XML layout but rater calling new MyCustomEditText.
As the developers site stated: The material theme design can only be applied when loading views using a layout inflater.
This is because the new material design backport hooks into the layout inflation process.
Another reason could be do to the fact that the appcompat v7 library only loads the material design when it finds an EditText in the XML layout. And it does not recognize custom view components.
Google plans to release the Material backport widgets in to the public, they stated that these are currently still in development. You may want to override these special backport widgets it could possibly solve your problem. But since they are not public yet... you can't.