chart: troubles using cost

Hi everybody!

We have some troubles when we try to display the curves. The cost
(from Project::actualCostTo(...) and Project::plannedCostTo(...) )
seems to return always 0 in our methods ( kptchart.cc =>
calculateActualCost(..) and calculatePlannedCost(..) ).

So we wonder 2 things:
- the two methods in Project,  quoted before don't work.(where should
we look at?).
- we don't know how to use the tasks's cost in KPlato (what do we need to do ?).

Thanks!