android XML view Does not display ToggleButton in Eclipse

in my android XML Graphical Layout, it can not display my ToggleButton. I get some errors (see below). Also I am no able to edit anything else using the Graphical Layout

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.thunder4apps.lanterna.corinthians.MainActivity" >



    <ToggleButton 
    android:id="@+id/togglebutton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textOn="Vibrate on"
    android:textOff="Vibrate off"
    android:onClick="onToggleClicked"/>


</RelativeLayout>

error :

Exception raised during rendering: -1
Exception details are logged in Window > Show View > Error LogThe graphics preview in the layout editor may not be accurate:
Different corner sizes are not supported in Path.addRoundRect. (Ignore for this session)
Path.isConvex is not supported. (Ignore for this session)