What is the exact meaning of "Result: The top level cell failed pin matching." for netgen? I have two netlists with matching components and number of nodes and it is giving that error. I seem to remember a more explicit error if the connectivity in the netlist is different.

This is supposed to be what results if you, say, swapped plus and minus terminals of an op amp. The network topology is the same on both sides, but when comparing what pin names are attached to what nets, the names don't match up on both sides.