Regarding non generation of reservation , and automatic generation of cost

Hi SAP, gurus,my problems is that im my case sap 4.7,while runnunig MRP, system doesnot generate req for the child parts, nor the reservation. In my case I want while saving the production oder, system must displays cost as i dont wants to go through calclator tab, or go to cost,---- ->cost view --.>itemization likes this.Pleses help me by guiding through suitable config. I have tried through transaction OPL8,determined planned while saving ,2, but the system say overhead key SAP1, is not being maintained.please help me how to maintain sap1 key also

thx

Please, .....