Your wave sample does not currently include any loop points that Yamaha's arrangers recognise!
I used Wavosaur to add loop points to the sample, and imported it into a voice using YEM. It then looped for as long as a key was held down.
Unfortunately, you will find that if you use the same sample for more than one note, the 'beat' will vary as well as the pitch, which presumably you do not want!
Ideally you would need a different sample for each note but all at the same 'beat', although you might be able to get away with using the same sample for say, three notes (its root note and 1 semitone above and below the root). The change in 'beat' might not be too noticeable, but you would have to be the judge of that!
Regards
Ian