how to set CirclePageIndicator icon in viewpager header

[chenfgit]

in layout.xml like this :
<com.viewpagerindicator.CirclePageIndicator
android:id="@+id/indicator"
android:padding="10dip"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
/>
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1"
/>

but it runs with error. I just want why ? thanks a lot.