android:digits Problem

Question

I am using the following xml to limit input to digits only in an EditText widget. The android:digits attribute uses the below array resource. Everything works great except for the fact that I can't enter the number 4 even though its in the array. Any Ideas?

<EditText
    android:id="@+id/mynumber"  
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:textSize="40dp"
    android:textStyle="bold"
    android:gravity="center_horizontal"
    android:layout_centerHorizontal="true"
    android:textColor="#aaffaa"
    android:numeric="integer"
    android:digits="@array/digits"
    android:background="#00000000"
    android:inputType="phone"
    android:focusable="true"
    android:singleLine="true" />

String array resource excerpt:

<string-array name="digits">
  <item>0</item>
  <item>1</item>
  <item>2</item>
  <item>3</item>
  <item>4</item>
  <item>5</item>
  <item>6</item>
  <item>7</item>
  <item>8</item>
  <item>9</item>
</string-array>