[SOLVED] Maybe bug with field "Validated cost"

It is not a bug, it is designed this way : project costs is defined from orders (if any exist).
Costs from resources are summed up to the project in "Assigned cost", "real cost", "left cost" and reassessed cost"

Amount you sell to customer will build the budget of your project.
Budget is alwaus without taxes (TVA) as you will have to reverse. It's nit your own .

Remember that financial items are to be concidered in the point of you of the project, not as an Enterprise module (ProjeQtOr is not an ERP).
Quotes : are quotes you send to your custumer
Order : are orders received from customers => so it is your budget
Bills : are bill you send to your customer to be paid.

When you receive the order (from customer), what you get is a budget for your project.
So amount of Order is defining "Validated total cost" for project.
But "Validated total cost" is also summed up from "Validated cost" and "validated expense", so Order amount has to be summed on one of these. It is summed on cost because Cost are more used than expenses...