Here's an example: A player has 1 remaining encounter attack power, that takes a minor action.
Divine Miracle is counterfactually worded as: "The first time you expend your last remaining encounter attack power each round, you regain the use of one encounter attack power of your choice.”
He uses the encounter attack power, recovers it with Divine Miracle, then uses a move --> minor action to use it again. He doesn't recover anything with Divine Miracle.
When the next round comes around, he has no encounter attack powers that he could use, so he can't "expend his last remaining encounter attack power" to trigger Divine Miracle.