Auto-Calculate Date value in SharePoint Field Definition.

Hi,

I have two fields Retention Period and Date of Destruction.

Retention Period is a dropdown with integer values from 1 to 100.

Need to auto-calculate Date of Destruction as Created + Retention Period.

Ex : 6/11/2014 + 10 = 6/11/2024, 6/11/2014 + 2 = 6/11/2016 etc..

I have tried using the Calculated Date Formula's mentioned at

(http://msdn.microsoft.com/en-us/library/office/bb862071(v=office.14).aspx)

i.e Calculated value formula for Date of Destruction as

However this is not working in SharePoint UI based column creation nor in Field Definition xml.

Am I missing something or going wrong somewhere.

Kindly help.

Regards,

Rivin