I got sharpness 5, unbreaking 3, fortune 3 and mending 1 on books for my new diamond pickaxe when I put sharpness 5 first then unbreaking 3 on the anvil I can't put the rest on because it says too expensive did I do something wrong.
Did you combine books to get the max level enchants? Every time you combine a book it becomes more expensive to apply it to an item. If the cost goes over 40 it becomes too expensive, no matter what you do. If you have repaired the pick in an anvil it will also raise the cost to apply enchants.
You must have combined several books to get the sharpness v (efficiency v?), because normally I use two eff IV books (combined to make eff V), mending, unbreaking III, and silk touch in my workhorse picks and the final enchant costs around 20 levels.