Android : image of button not changing when pressed

I my app i have many buttons,what i want is that when user selects particular button,its background should change so that user knows which button is selected.So for this i have used selectors.But when ever i run my app the event on button click works fine but the button image doesnt change

Selector

<?xml version="1.0" encoding="utf-8"?>

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:drawable="@drawable/people_1" android:state_selected="true"></item>
    <item android:drawable="@drawable/people_1" android:state_active="true"></item>
    <item android:drawable="@drawable/places_1" android:state_focused="true"></item>
    <item android:drawable="@drawable/hotel_icon"></item>

</selector>

Xml where i used the selector

<Button
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/hotel"
                android:layout_weight="1"
                android:id="@+id/home" />