Ken is away on a trip, I think. I have a big staghorn too, but it's permanently attached to a huge oak tree and I do nothing for it except throw a few coffee grounds up there occasionally.
They do like humidity, and feed off stuff that falls from the tree, in the 'wild'. So possibly you should have been misting it with a little bit of very dilute fertilizer occasionally. If the plaques (leaf bases) are still green you should be ok. Remember they really feed mostly through their leaves. The roots just hold the plant in place for the most part. That means the potting medium doesn't matter all that much. I'm pretty sure Ken grows most of his mounted on wood, so basically no soil or moss at all.
