I am concerned ... once you have a PAL it remains on the form 8582 until such time as it can be used up or more is accumulated. So did some of the prior year unallowed losses get used up along the way or did they get lost/forgotten? Review the 2009 & 2015 returns ... did the loss get used/absorbed ?
Usually the sale of a rental is pretty straight forward if you go slow and read all the screens carefully but I highly recommend you seek local professional assistance if you cannot see where the prior year carryover losses went to.
