LCROSS was going to crash into crater Cabeus A. But after analyzing data from spacecraft such as the LRO, the Lunar Prospector, Chandrayaan-1, and Kaguya, the impact site for LCROSS has been changed to Cabeus (proper), a bigger crater close to Cabeus A. This determination was made because the hydrogen content and terrain suggests that crashing into Cabeus rather than into its satellite crater would give the best chance of observing water in the resulting plume.
