[Zeke]

Man, I could go on this one for days, but I'll let everyone tell their advice. I'll just start with tile should not have a hollow sound once set. If necessary, each tile might have to be "back buttered" before setting into the grooved tile set. The more irregular the tile, the deeper the notches in the spreading trowel and the more need for the additional mortal on the back side of the tile.

To me, all of the answers are obvious. If they don't get explained overnight here, I'll weigh in again. Clues: too much water and not enough. Sorry, that's as far as i can go, I'm tired and my spelling corrections are taking more time thatn the message.