When updating the Order Numbers on a Trade Contract, any existing collections are not updated by default. If the jobs have been completed and a transaction exists, you need to either update the transaction or, for a batch of jobs, use the Update items En Mass function.
If the job has not been completed:
Go to the Contract
Depending on whether the Order Number is for the entire Contract or for a single Item on the Contract, edit the Contract or the Item.
Under the order reference, or item order reference is a yellow box for updating missing references.
Enter a from date for when jobs need to be updated from, or if everything from today, leave blank, then click Update uncompleted collections; this then flushes through to any jobs that have not yet been completed.