AUC With Internal order Budjet?

Dear All,

Creation of internal Order;

1. we have created an internal order - KO01

2. Assigned budget in KO22

3. In settlement selected receiver category as asset with  full settlement

4. Created AUC with internal order maintained

5.  Created PO, in ME21N, but here system is asking G/L?, which G/L has to be input   

Client Requirement is as follows:

They have one G/L AUC Buildings ( B/S ) in legacy... here they are capturing all the building related values for the same G/L till capitalization.

Can anybody explain full process cycle right from AUC, Internal order and settlement with example and T codes?

Anil