Error:Enter a valid lot size.

When we creation a new material ,system give a message: Enter a valid lot size. but seems everything is ok . so what happened?

Enter a valid lot size (materials planning)

Message no. M3497

Diagnosis

The lot size specified in materials planning does not make sense here since quantity updating is not defined for the current material type in the plant specified.

Procedure

Choose a lot size for which the lot-sizing procedure "lot-for-lot order quantity" is defined.

According to this clue ,we found that we didn't maintained quantity and values update in this new plant .
IMG path:
  Logistic - > Material Master -> Basic Setting -> Material Master -> Define attribute of Materials ->  Quantity/Value Updating .

After you done this step ,this error will be eliminate .