saccing a land and not finding anything

[jazzykat]

If I slave someone and they have a fetchland, I can force them to sacrifice it, pay the life, then search (unsuccessfully if I chose) for a land correct?

Someone online told me that I must  find a land. What if they have none left in there deck or none of the appropriate type?

[Jebus]

Since you are searching a non-public zone for a card with specific criteria, you do not have to find it.

[Komatteru]

On a side note, if, for example, you are searching with Demonic Tutor or Vampiric Tutor and there are any cards remaining in your library, you cannot fail to find.  Similarly, you cannot take less than 5 cards with Doomsday if you have 5 or more cards remaining in your library.

[jazzykat]

thank you. some of the people who play on MWS are fucking dumb. I was told that a mindslaver and welder is a noob combo :B