Android : Keyboard won't show when EditText is clicked in DialogFragment

I am using a Dialog Fragment with a custom layout. The DialogFragment has ListView. Here is the xml for the items in the ListView:

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

    <Spinner
        android:id="@+id/nutritional_selection"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <Spinner
        android:id="@+id/greaterThanLessThan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:ems="5"
        android:id="@+id/amount_edit_text"/>    

   <Button
       android:id="@+id/destroy_button"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="destroy"/>
</LinearLayout>

When I open the DialogFragment and click one of the EditText's, the EditText is focused on, but the keyboard isn't shown. How can I get the keyboard to show?