And to be clear, all of those things MayaD mentioned, and perhaps a few others, are indeed distributions even though the gross amount of the distribution did not end up as cash in your pocket. If you received a Form 1099-R, you almost certainly received a distribution.
One of the only cases where it not too unusual to receive a Form 1099-R when you should not have is if an IRA was moved by nonreportable trustee-to-trustee transfer but mistakenly reported it as a distribution. A trustee-to-trustee transfer of an IRA is neither a distribution nor a rollover.
