This may happen for a number of reasons - perhaps the pieces of beef were too big and need a longer cooking time, or maybe the cooking valve wasn't sealed properly on the pressure cooker. u003cbr/u003eu003cbr/u003eEither way, u003cemu003epop it back into the pressure cookeru003c/emu003e (with the cooking liquid) for another 15 minutes (making sure the valve is sealed)