I am baking three 12" round cakes (separately) using DH French vanilla box cake mix & using the extender recipe. First cake turned out fine and the next two have a hard crust like top and it is wet inside when tested w/ a skewer. Anyone know why and what I can do to prevent this?

Cant understand why the first came out fine and the other two arent. Check whether you are baking it at the same temperature of the first cake OR have you accidentally added extra liquid ingredients. You may be able to place a piece of foil on top of the cake while baking, to prevevent it crusting on top. Are you baking it on the middle shelf?