Put the summary of the bug you're having here
What I expected to happen was...:
when I enchanted the boots I thought I was going to get frost walker boots
What actually happened was...:
when I clicked on the final slot the BOOT WERE GONE!!!!!!
Steps to Reproduce:
1. go to an anvil
2. ...use the frost walker 2 book then put in the boots in the second slot
3. ...then click on the final slot and...GONE PLESE FIX!!!!!!! AHHHHHH!!!!!!!
Are you sure you're on 15w44b? Please force a crash report by holding F3+C for 10 seconds and attach the resulting crash report here.