Britney Spears Sings Happy Birthday On X factor

I feel like someone told Britney Spears to take the cake out and go sing Happy Birthday like you are singing the National Anthem at the Super Bowl. The first few times I watched it, I felt sorry for her, because it is so awkward with her being the only one singing. No one wanted to join in? Would Britney only sing if she could have a solo? She seems kind of nervous, but I thought she did a good job, just way over the top. Does anyone else feel like there is nothing beyond the eyes, like she is in some kind of haze and just does what she is told.