G/L Account Substitution Rule during FI-AA posting

I have setup a new transaction type Z01 to retire an asset for impairment processing. I used a substitution rule in order to replace the default disposal G/L Account to post to the correct impairment loss account. In the FI line item substitution rule, I provided if "Transact.type = 'Z01'" (BSEG-ANBWA), replace BSEG-HKONT (G/L Account) with the impairment loss account. When I ran a test, the transaction didn't call up the substitution rule during FI-AA posting. However, when I looked at the BSEG table, the line doesn't have the transaction type associated with it.

Any thoughts/suggestions to accomplish the G/L account substitution during FI-AA posting??