I think you've miunderstood what you picked up. You can't craft Skill Shards. You picked up a shard called "Skill Shard: Crafting". The colon is important. It means it's a skill shard that gives you XP towards your Crafting skill. It doesn't let you craft skill shards.
If you looted "Skill Shard: Crafting" when you pick it up it automatically grants 400 crafting xp.. Is this what you are referring too? Or do you have an item in your crafting blueprints that says Skill Shards? Can we see a screenshot?