If you did a CE download on a H21 then the software level should be 0x42ce, if not then it didn't work.
If you did the edgecutter correctly then when you go into the menus, then "Parental, Fav's & Setup" there will be a Miscellaneoud Options selection, in there you need to turn MultirooDVR on.
If you've done all that you need to go back and make sure that the network connection on both the H21 and the HD DVR are working correctly.
Excuse my ignorance. I have an HR20-700, H21-200 and H20-100 in my setup. The HR20-700 is networked to high speed DSL.
I tried twice to download the new release on the H21-200 and the H20-100 Saturday night and it appeared to be upgrading the H20-100, but no Misc Options in the PFS. The H21-200 would not upgrade. I suspected this might because the receiver is out in my shop and does not a phone connection. I have since learned you don't need a phone connection to get the upgrade. So, I don't know why it wouldn't upgrade.
I just learned yesterday that I need a network connection on each of the receivers, which I just ordered from DTV. Hopefully once it connects I'll be able grab the next download window. I'm a glutten for anything new so I'll try any upgrade that comes down the pike.
Again please excuse my ignorance, but I'm learning. I've been a directv subscriber since it first became available many, many years ago, but just started looking into these cutting edge downloads.