Advancement question

[ShadowWalker]

I have a game system that increases the cost of increasing skills as they level.
How can I set the value of the field advCost to current value of the skill + 2.

I've added code to the advance component using
perform gizmo.findchild[none,"Advance.Gizmo"].setfocus
and
perform gizmo.child[advDetails].setfocus

to access the skill that was selected and the first seems to work. Except that all the fields are default values. It doesn't seem to matter what the phase and priority are set to, the values come back default.
It just came to me that this won't work without saving the value of the skill at the time the advancement was added, or the order they are processed in is important.

I know this has to be possible since Shadowrun works this way.

Any ideas of the direction to go in would be greatly appreciated.

Thanks,