In-camera AWB is iffy and approximate at best, and especially in mixed-light situations is easily fooled. I use UniWB (do a forum search for more info) in-camera to maximize the accuracy of the histograms so I can adjust exposure more accurately, and then set WB manually in the RAW converter, using the RAW converter's Auto WB setting as a starting point. UniWB makes the previews on the camera LCD look funny, but makes it easier to get exposure right, especially in oddball lighting where blowing a color channel can be really easy.