仿真中找不到“dc”工作点

CPU times:
       91.9u sec/nonlinear device/timestep
       43.8u sec/nonlinear device/Newton iteration

execution time= 0.0156 sec.
messages given: 1 error
>
tr (monitor 100,tend 100m,tstep 10u
*** ERROR "CLASS_IP_NOT_FOUND" *** The initial point "dc" is not found.
tr (monitor 100,tend 100m,tstep 10u
                                    |
>
pl (plaction openonly
execution time= 0 sec.

这是什么问题，谢谢！