Check the presets in the beer program. Lots of info to input such as wort loss, evaporation rate etc. Also, make sure you end with the same amount of pre and post volume. If you end with 6 gallons, but beersmith is calculating 5, your wort would be watered down. Ensure you are taking hydrometer readings at room temperature, you will get false readings (even "corrected") if the wort is too hot.
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