Using Data Validation combine with If statement with 3 accounts

[Krazee]

I am trying to write an If statement using Data Validation drop down for a combined bank ledger. I am having trouble getting data to filter properly. I can get it to function with 2 selections but when I added the 3rd i can't figure out the statement order. Any help it appreciated...

=IF(E3="",G2,IF(E3=$AJ$2,G2+AI3,G2+AI3))

COLUMN E IS FROM(DROP DOWN)
COLUMN F IS TO(DROP DOWN)
COLUMN G IS HUSBAND BALANCE
COLUMN H IS WIFE BALANCE
COLUMN I IS SAVINGS BALANCE
COLUMN AJ IS DATA SET FOR DATA VALIDATION DROP DOWN