Noob: TList Question

Well.. I'm still stumped! I want to create a tlist of different objects and just iterate through a list and call each objects update and render. Sumpin like this:

'
Type TObjects
 '
 Field TObjectsList:TList
 '
 Method Update()
  For Local o:Object = EachIn TObjectsList
   o.Update()
  Next
 End Method
 '
 Method Render()
  For Local o:Object = EachIn TObjectsList
   o.Render()
  Next
 End Method
 '
End Type
'
Type TBaseObject
 '
 Field x:Float,y:Float
 '
 Method Render()
  ' draw here
 End Method
 '
End Type
'
Type TObject1 Extends TBaseObject
 Method Update()
  x = x +1 
 End Method
End Type
'
Type TObject2 Extends TBaseObject
 Method Update()
  x = x +1 
 End Method
End Type

But this little bit of code won't even compile. Says it can't find "Update". Any help is appreciated, thanks.