关于Saber仿真的问题。

在网上下载了一个Saber仿真反激实例。不做任何更改是可以仿出来的。当我该变一个电阻的阻值参数后出现了这条语句：“ Cannot perform alter command. You must re-netlist this design before doing any simulation.” 然后我保存再仿真就出现了两条错误:*** ERROR "ALG_NO_SOLUTION" *** Cannot find nonlinear system solution.

               *** ERROR "ALG_NOT_FINITE" *** The nonlinear solution yields a value that is Inf or NaN. Increasing nsdensity (currently 1) may help.

请问如何在搭建好的仿真实例上再进一步的修改仿真。我也是刚用Saber，请大家不吝赐教。