Unable to check CheckedTextView from UI?

Question

Here is my list item:

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

<CheckedTextView
android:id="@+id/title"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:textSize="25sp"
android:checked="true"
android:checkMark="?android:attr/textCheckMark" 
/>

</LinearLayout>

But when I try to click on the checkmark in the emulator, it doesn't uncheck? What is causing this? Did I forget to implement something in the onListItemClick method?