Approval Templates Error Message

Hello Expert,

I am a new user of SAP B1:

I need a user to be able to create A/P Invoice Draft instead of posting the A/P Invoice to G\L...

When I go to Administration>Approval Procedures>Approval Templates, I have a list of users who usually create A/P Invoice Draft for Approval..., I notice that the user who have to create draft is not listed.

When I insert the user in the list, sap return this error message after clicking on 'Update Button' :

*Fixed terms cannot be selected when the 'use terms flag' is false Message 3621-12*

How can I resolve this issue?...

Thank you...

Ben