XML Repeating Fade Animation

I would like to animate a view in my app. It should do the following in an infinite loop:

• Be fully visible for 250 ms


• Fade out over 250 ms


• Be fully invisible for 250 ms


• Fade in over 250 ms

According to some references I found on the internet, the following should work:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://ift.tt/nIICcg"
    android:interpolator="@android:anim/linear_interpolator"
    android:repeatCount="infinite"
    android:repeatMode="restart" >

<alpha 
    android:duration="250"
    android:startOffset="0"
    android:fromAlpha="1.0"
    android:toAlpha="1.0" />

<alpha
    android:duration="250"
    android:startOffset="250"
    android:fromAlpha="1.0"
    android:toAlpha="0.0" />

<alpha
    android:duration="250"
    android:startOffset="500"
    android:fromAlpha="0.0"
    android:toAlpha="0.0" />

<alpha
    android:duration="250"
    android:startOffset="750"
    android:fromAlpha="0.0"
    android:toAlpha="1.0" />

</set>

In practice, the view is fully visible and does not fade. Does anybody know what the problem is here?

Edit:

The code in the view in which I start the animation looks like this:

Animation myAnimation = AnimationUtils.loadAnimation(context, R.anim.my_animation);
startAnimation(myAnimation);