Calculating symmetry

Hello again.
The manual states:

Calculate By Topology
(...)
Use LMB to pick vertices between two symmetrical polygons vertex by vertex in a constant symmetrical order. Once the programe has gathered enough information, it will automatically carry on to perform symmetry calculation.

Let's say we've got a sphere with an edge loop on its equator. I wish this edge loop to be the symmetry plane (not literally of course). I enter the Calculate Symmetry tool and select Calculate by topology. I then pick the first vertex right above the equator, then a corresponding one on the other side of the equator. A dotted gray line is created by NVil.
And this is when I'm lost. I think I'm supposed to pick next vertices in the similar manner - one from one side of the future symmetry plane, one from the other and so on. But the thing is that NVil doesn't allow me to pick every vertex I want. I have to guess which one will accept the mouse-click. I always end up with several gray, red and green dotted lines and no symmetry at all.

I've been trying to understand what is going on here for at least and hour to no avail. Is there any additional detailed info about symmetry (and mirroring) in NVil?

rubberDuck, there are quite a few tools for symmetry calculation. The vertex one is the most complicated one but the most reliable one so use it only if you failed on other tools. There are two under edge tools and one under subobject tools.

By the way, have you got the 3D-Coat 4 applink working yet?

Okay, I found some other symmetry commands in the Common Modeling Shortcuts section. I believe they are the ones you had in mind? Indeed those tools are much simpler than Calculate Symmetry from Vertex Shortcut Tools section.
Nevertheless it would be nice to know how to properly do vertex symmetry (be it Calculate by topology or Calculate by vertex position).

About the 3D Coat AppLink - I've only tried it a bit. Exported an object to voxel room and to UV room to check if it works and indeed it seems to do what it's supposed to do. The only problem I have is with the mesh scale in the voxel room, because it appears so tiny that it's almost invisible. But it's most likely caused by scene scale settings within 3D Coat. I will have to take a closer look at it at some point in the future.

How did you know I use 3D Coat?

Sorry, I thought you were somebody else
http://voidworld.cmcproductions.co.uk/index.php/topic,1019.msg3245.html#msg3245

There is an scaling option for exporting to 3D-Coat. Edit > Options > 3D-Coat Applink Settings.