When receiving a multi-level tracked serialized part, system validates that each serial number has “enough” components assigned in it’s tracked structure. So basically according to the Quantity per Assembly.

Now you can either let the system automatically assign components to each parent serial, or do this manually. A site setting controls the behavior.

 The message is raised since at least one of the received serials does not have assigned components according to the quantity per assembly. You can use the Shop Order As-Built Structure (Shop Order Tracked Structure in IFS Cloud) page to see and edit the assignments. 

If you are not interested in creating as-built structures, you can also choose to disable the multilevel tracking flag on the Part page,.