Did you try simulating it in transient to check it actually oscillates? Also, are you using a current version of the simulator (i.e. not spectre from IC5141 which is ancient, as there have been 10 major releases of spectre (in the MMSIM stream) since then. OK for you to be using IC5141 as the schematic and simulation environment (you may be limited by your design kit), but the simulator should be something more recent. But either way, you need to check the simulation in transient to ensure that it's actually working.