If you appointed Auditor at AGM held before 30.09.2011 for the financial Year 2011-12 then date of AGM held in 2011 will be mentioned.
For example:
1.Financial Year for Adoption of Balance Sheet: 2010-11 2.Date of AGM for the Financial Year: 30.09.2011 3. Auditor Appointed at AGM on 30.09.2011 for the Financial Year 2011-12.
4. Date of AGM to be mentioned in Form-23B for the Financial Year 2011-12: 30.09.2011