Hello,

Yes.. you are in Joomla 2.5? it's weird that you're getting this error.. but in any case all you would need to do is to remove the "Legay" part.
if you want I can do it quickly by code. if you want to do it yourself, just open that file it tells you, and go to line 20.

there where you see: JControllerLegacy

you should put: JController

it is possible that it will ask you to do the same for the class JModelLegacy and JViewLegacy....

let me know