Guess Im gonna have to go back and re-read the final fight again. Thanks for the answers.
Voldy could have been thinking that he has now cast the AK curse TWICE and both times it failed to kill Harry. (Once as a child and again in the forest.) But if he could only "get his hands on the Elder Wand" then maybe the AK curse would finally work. Or else, why would Harry put so much effort into trying to convince Voldy that he (Harry) in fact had the Elder Wand? In addition, Harry had already used two of the three "unforgivable curses" so.....