Go to Settings - Salary items :

Position yourself on the item  (DO NOT uncheck it):

On the Global tab, (which becomes grey as soon as the item has already been used), the type of item must be  Health insurance (loss of earnings) and the field Social deductions item must be ticked..

On the Computation Elements tab, the Active for Minors and Active for pensioners boxes must be checked.

The box End of period adjustment must be checked as well.

The insurance contract must be the one that was defined. (In case of doubt about the settings, see here )

In the tab Applied to, you will find the items to which the DII is applied :

On the Subject to tab, there would be items to which the DII would be subject. Therefore, there are no items checked:

On the Statistics/Certificate tab, the Group of fields is Social contributions and the box Health insurance IJM must be checked