Android: after installing an APK, the open button is disabled

I read in so many places that the problem is related to the manifest and the definition of the first activity. It seems that I'm doing fine but still the open button, after installing the APK, is disabled and I don't see the icon on the device

<application
    android:allowBackup="false"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="@string/google_maps_key" />

    <activity
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
            <action android:name="android.intent.action.VIEW"/>
            <category android:name="android.intent.category.BROWSABLE" />
            <data android:scheme="http"
                android:host="www.example.com"/>

        </intent-filter>
    </activity>
    <activity android:name=".DateSelectorActivity"
        android:label="@string/app_name">
    </activity>
</application>