Why is that? Since the Torah said, "You shall take for yourself, on the first day of Sukkot holiday, palms tree branches," they should belong to yourself. And stolen branch does not belong to the thief. However, this only resolves the matter for the first day. What about the second day?
Rabbi Shimon, the author of the Zohar, gives the rule: it would be a good deed brought about through transgression, which is not valid. But why is this so? Why not say that the end justifies the means? It is because of this: "You bring the stolen, the lame, and the sick animal - shall I accept it?" Just as lame cannot be fixed, so stolen is forever disqualified.
But let's analyze this further. The thief steals the goods. The owner has not given up and hopes to get them back. At this time, the object does not belong to the owner, and a mitzvah that should be done with one's own object is invalid. But later, when the owner despairs, the object belongs to the thief! And yet, Rabbi Shimon declares it invalid. This tells us that one cannot do a good deed through transgression.
This opinion is not unanimous. Shmuel disagrees and says that it depends on the situation. He says that just as you can borrow a lulav and thus make it yours for performing the commandment, so is the stolen lulav valid starting from the second day of Sukkot and later.
Art: The Cunning Thief by Paul-Charles Chocarne-Moreau