[Q] setAlpha() in Android Lollipop topic

Hi there!
I tested my app on Android Lollipop, and I noticed that setAlpha(int value) is not working...
I saw on the Android Reference that setalpha(int) is for 11 below API, and setAlpha(float) for higher APIs.

I tested the app on Android 4.0 (API 14) and it works perfectly... But when I tested on Lollipop (5.01, API 21), the setAlpha doesn´t work :S

What Can I do to solve this porblem?