Hi @Abdessamad 

Can it be due to your inventory setup? Please review cost control on inventory part. See if Zero Cost field is set to Zero Cost Only

Hello, 

Thank you for your help.

Can you explain what this setup is used for ? 

Because I tried it, it works but i didn’t understand why.

Best regards.

Hello

I will copy for you help description. 

Zero Cost:
The value can be either Zero Cost Allowed, Zero Cost Forbidden, or Zero Cost Only. This field specifies whether or not the part can have a standard cost of zero (0). Generally, the system requires that the part be cost calculated and has a standard cost. By allowing zero cost, exceptions from that rule can be made. If zero standard cost is allowed, cost accounting for inventory movements of this part will receive a zero (0) value. If zero cost is forbidden, you have to estimate a material cost. This field cannot contain the value Zero Cost Only if you are using the Weighted Average as the Inventory Valuation method.