I made meatballs a night ahead with the intention to grill them. 1 lb lamb, 1 lb beef (coarsely ground by local butcher), 2 eggs, flour and attendant spices. They refused to stick together, and crumbled on the grill. They didn't even stick together after pulling them out of the oven where we finished them off in desperation (Chicago in near-100 degree heat). What did I do wrong?