Trying to push a button to bottom of linear layout in Android

Question

I know this can be very easily done by using a Relative Layout but I feel what I am doing is correct and should give me the desired result with the Linear Layout itself. But for some reason, when I run on this on Google Nexus 7 running Android JB 4.1.2, I see the button and the text view immediately after the list view items. If the list view is empty, I see them at the top of the screen. Am I doing something wrong?? Here is my xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/attachments_list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1"
android:orientation="vertical">
<ListView
    android:id="@+id/mtg_attachments"
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />
<Button
    android:id="@+id/attach_delete"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:text="@string/delete"
    android:textSize="22sp" />
<TextView
    android:text="@string/attach_warning"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="18sp" />
</LinearLayout>

Answer 1

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/attachments_list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:weightSum="1" >
<ListView
    android:id="@+id/mtg_attachments"
    android:layout_width="fill_parent"
    android:layout_height="70dp"
    android:layout_weight="0.9" />
<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom"
    android:layout_weight="0.1"
    android:gravity="bottom" >
    <Button
        android:id="@+id/attach_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="delete"
        android:textSize="22sp" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="attach_warning"
        android:textSize="18sp" />
</LinearLayout>
</LinearLayout>