Star Trek: The Next Generation - Another Contraction for Data
In the episode " Clues " right at the start, Data is practicing portraying Scrooge. Marley asks " you dont believe in me ?" Then Data says " I don't !"
[Actually, the correct episode was "Devil's Due" when he is playing Scrooge.]
He's reciting a line, not speaking in his own words. Just because he can't use contractions in every-day speech doesn't mean he is incapable of pronouncing/reading them.