SAP PS

Dear Guru,

How are you?Hope you are doing well.I have confiquered PS in my sandbox server.we have created Order,WBS Elements. Now i did a Purchase Order for the Project.But the purchase order cost is not affecting the project cost.

Can you please tell me , whether the purchase order cost will affect the total order cost.can you please tell me,where and what are the effects of project system in other modules.

Thanks in advance

Satya