Everyone's different to some degree, but things that usually cause me to miss wide:
1) Pushaway goes too far to the left, causing a figure-8 motion that sends the ball right. This is useful when I want to get in and hook it, but not if I'm trying to play more direct.
2) Turn my hand too early.
3) Body rotates right during my approach, particularly on the slide step.
4) Timing goes awry somehow, resulting in getting off-balance during my approach, or getting to the foul line early or late.
5) Losing balance because I lean too far forward with my body.
...And that's just
some of the reasons for me.