PJM Interconnection Interview Question

Questions were easy for an experienced Java, Spring developer. I thought i had good interview but was not selected by them. Reason??? i answered most of the questions from my practical experience but it seems they were expecting the answers straights from book. I was bit shocked of being rejected as i was expecting face to face interview call after tele interview. I had one more telephonic interview that day in a leading bank which i thought wasn't as good as i did in PJM call. I passed that one and all four face to interview next week and got an offer there.