why is my sugar/dates boiled syrup crystallizing when added to rice krispies/chopped nuts when making date balls?

my recipe requires no syrup. the dates melt down over heat, w/ butter; then rice crispies are folded in. form into balls, roll in conf sugar. the end.

Crystallization occurred because you added a nucleation point (i.e. the rice and nuts). Because it's a sugar and date boiled syrup, crystallization can occur even with a grain of sugar. I've read that adding corn syrup or a small amount of cream of tartar (~1/4 tsp) will help stabilize the sugar syrup and keep the sugar from crystallizing out. But I don't know what effect that would have on your recipe.