请问为何CheckedTextView控件在RelativeLayout内不动作

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    >    <TextView         android:id="@+id/text1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginLeft="10dip"         android:layout_centerVertical="true"         style="@android:style/TextAppearance.Large"></TextView>    <TextView         android:id="@+id/text2"         android:layout_alignLeft="@+id/text1"          android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginTop="12dip"         android:layout_marginLeft="66dip"         style="@android:style/TextAppearance"></TextView>    <CheckedTextView         android:layout_width="fill_parent"        android:layout_height="?android:attr/listPreferredItemHeight"        android:textAppearance="?android:attr/textAppearanceLarge"        android:gravity="center_vertical"        android:checkMark?android:attr/listChoiceIndicatorMultiple"        android:paddingLeft="6dip"        android:paddingRight="6dip"></RelativeLayout>

SimpleAdapter listItemAdapter = new SimpleAdapter(this,listItem,                    R.layout.list,                 new String[] {"text1", "text2"},                 new int[] {R.id.text1, R.id.text2}        );listView.setAdapter(listItemAdapter);listView.setItemsCanFocus(false);listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);