Importing custom campaigns from the original game or HD to DE

There seems to be a dearth of decent custom campaigns for AoE2 DE so I wanted to try to see how I could get the original version custom campaigns to work in DE. And by original, I mean files ending in .cpn or cpx.

I've attempted to run "The King's Best Men" by Ingo Van Thiel from Age of Kings Heaven and it isn't even "seen" by the game so I'm thinking it's not as simple as merely renaming the extension of the file from .cpn to .aoe2campaign.

Anyone have any ideas?