Final Control Report: Why do I get the validation Error that the Document type "Closure Declaration" is missing, when I have already uploaded it?

If you receive the following error message upon validation:

Firstly check that you have uploaded a document of this type for each CCI concerned by the Final Control Report.

Secondly, check that you have added the CCI number to all the documents of this type. To do so, first click on the Edit link in the Associated Documents section:

Select the document title for this document type:

Make sure the CCI  number has been added (1) and click on 'Save' (2):