Two things - did you tune your guitar before playing and make sure your intonation was correct? It can often be over looked. Secondly - did you match the E note to the right E note on the keyboard of Sample One when assigning the note? E.g. top E string played open is classed as "E4". Did you place your sample at E4 or just place it in it's default middle C (c4) position? If you didn't map it right it will sound off.