Remote will not work with new receiver

I have just had my Directv receiver replaced with an HR 24 500 - one step up from my previous one I have been told.  Unfortunately, my Directv remotes, which continue to control my tv, will not work with the new receiver, which is also a Directv. . The codes I've tried are 00001 and 00002. I'm stymied, as the literature says the remotes will work with any Directv receiver. I've tried all of the above suggestions but without success.