What needs to be fixed?
Sounds like its working normal and well. If you are having issues with failing, skill up more.
Resources are very very cheap and easy to get. Failing 7 times to make a cart isnt much at all. Sounds like you are trying to do everything on your own without trading or putting effort into training up the skill.
Also dont forget you can drop skill points into it from your exp skill points every time you level up.