On several occasions when enchanting tools, despite taking my Lapis and XP, my tool remains un-enchanted. This is happening more frequently and is very frustrating when you think you have enchanted your pick axe with Fortune III only to find that it hasn't worked. Then, when you go back to re-do it, the option for Fortune has gone and has been replaced with Efficiency I (for 30 XP). Please fix this, it is most annoying!