Sales contrat: manage posting on tax for discount on application for payment

Hi,

I ‘ve generated  a project invoice  with discount  from  application for payment.

So I ve set up AFPI3 (Project invoicing discount).

I ve  checked the posting, and I dont have the tax with the discount , I ve only for the tax for customer invoice part but not for the discount. How can I do it?

see joined a posting example:

we have a customer invoice  18331,20€  ( 16000 net amount + 3131,20 tax) and the famous discount 800€

In the posting, the discount doesn’t have the tax amount part 

Thanks a lot