Oxymercuration demercuration, PCC, NaCN/HCl reaction In this reaction of the alkene, the correct answer is below but I don't understand why it goes to that. This is my thought process - reagents 1 and 2 do oxymercuration demercuration and makes a secondary alcohol, then reagent 3 turns the alcohol into a ketone, and finally reagent 4 and 5 performs nucleophilic addition and turns the alcohol into a tetrahedral with CN attached (my steps I drew below). What am I doing wrong here? Thanks
Check the mechanism of the last reaction here. 
http://www.chem.ucalgary.ca/courses/350/Carey5th/Ch20/ch20-3-5-1.html

It is not the displacement of nitrile by carboxylic acid(which you do not have, btw). It is the combination of water addition and the displacement of ammonia by second equivalent of water.