4 cubs died prematurely after mother was tranquilized.

This tigress was shifted to bandhavgarh national park from different place after tranquilizing. A pregnant Tigress was tranquilized and later all her 4 cubs died. Apparently forest department was not aware of her pregnancy. My question is then what were they monitoring since so many days? Or did they tranquilized a different tigress and got her to Bandhavgarh National Park by mistake?