Paladin Smite

First time I did a paladin smite the system said it could not find my spell slots level 1, although it allowed me to do it. I used it twice during the battle and neither time did it deduct the level 1 spell slot (I has 3)

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On the second occasion it rolled 3 times for some reason, and then correctly applied just the first roll of damage. The hit was a critical, so I dont know if that caused it