TAB setting for natural account

Summary

TAB setting for defaulting natural account based on category

Content

Requirement: I have a requisition preference set where I had entered a default account code combination. My requirement is to override the natural account segment of the code combination based on the category selected.

Setup Step (screenshot attached):

1. Defined Mapping Set and entered natural account against each category

2. Created Account Rule and attached the Mapping Set

3. Entered the Account Rule in the natural account segment of the Charge Account row in TAD

4. Changed the TAD value in the SLA option 

When I created Requisition, the Charge Account field remains blank. I am not sure what I am missing in the setup.