I don't understand what's wrong? (Crafting)

example: if your wood is lvl 10 and your gem is lvl 15 it wont work

if youe wood and gem are lvl 10 but your ingredient is lvl 20 it wont work

(i think)

 

The level range for your crafted item needs to be at least the level of your highest level ingredient. If you click the up arrow above the check mark, you can increase your craft item's level range (assuming you have the profession level to do so).

Weaponsmithing level 1-2 can only craft items of level 1-3, WS level 3-4 can make items of level 3-5, WS of level 6-7 can make items of level 5-7, etc.
If you are making items that are only level 1-3 because you haven't changed the range after leveling up, ingredients that are level 5 can't be made because the crafted item's levels aren't at least 5.
Changing the range to craft level 3-5 weapons should work, if not, then the range of 5-7 will definitely work.