Button under ListView not visible in Android

I am working on some ListView I want to display a Button under it I am using the following code but that is not working.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:cacheColorHint="#00000000"
    android:drawSelectorOnTop="false" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button" />

</LinearLayout>

the button is not visible, why?

List view takes the full page. Try to give desired weight to the elements to your code. Use this code,

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:cacheColorHint="#00000000"
    android:drawSelectorOnTop="false"
    android:layout_weight="5" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button"
    android:layout_weight="1" />

</LinearLayout>