How to Enable Default Expense A/c Based on the Item Category ?

 Hi All, I have created the Employee who is Requester too and Under Assignment Tab of Employee in the PO Information i have define the GL AND Corresponding Charge Account to the Requester / Employee. 

There after I have also define the Expense Account Rule for the Specific Item Category. 

Now when I am trying to Create the Requisition from the Same Item Category to which Me assign so It Default the Expense Charge Account which Lies under the Item Master Purchasing tab no the Account not that A/c Which me enter into the Employee and Expense Account Rule. 

I think any Setup is Remaining dont know what is that but that for sure any part is missing in it.