Accounting entry rule-pls advice

My question is "will an expence a/c credit  or income a/c debit in an entry at any circumstances...

Situation by which I am asking this is..

1.I have withdran 2000 rs from bank against salary of a staff against a voucher.

but his salary was 1900/- and I paid 1900 only.My boss told me to deposit back that 100/- rs.

in this case I passed an entry at 1st: Salary A/c ........dr

                                                                   Bank A/c..........cr

NOW I WANT TO KNOW WHETHER THIS IS CORRECT OR WHAT ELSE IS THE ACCOUNTING METHOD TO MAKE A ENTRY FOR DEPOSITING BACK 100/-rs

I made an entry         Bank A/c...................................DR

                                    Salary A/c .................................CR

Thanks In Advance

Renjith S Nair