When an effect allows a player to search his/her deck for a card, that card must be found if possible. A deck is always shuffled after a search effect, even if the searched for card was unable to be found.

Page 4, Column 2, Paragraph(s) 5, FAQ
If a player is searching for a card, he must find the card, if able. If a player is unable to fulfill the condition of the search, then nothing happens, but the deck is always reshuffled.
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