ClassCastException when using DrawerLayout and the main content is RelativeLayout

I have like the following

<DrawerLayout. ..>
     <RelativeLayout../> -----my main content
      <FrameLayout Gravity="start".../>  drawer view
</DrawerLayout>

this gives me ClassCastException can't cast LinerLinearLayout to RelativeLayout in this line child.measure in the DraweLayout class sorry I can't copy the exception as it because i'm on my way to home and asking from phone. Wil edit it when I arrive

Thanks in advance.