Calendar change from Fiscal to Calendar

Hi

We are working on Calendar Change from Fiscal to Calendar

We followed the steps as per note : 102460.1 , 

The steps shown in this note shows changing the calendar from the next sequential year

For example : Suppose my current period is MAY-16 Fiscal , i.e 01-MAY-2015 to 31-MAY-2015 , and i need to make the calendar change effective next year i.e 2016 onwards itself , such that my new Calendar year will start from 01-JAN-2016 to 31-DEC-2016 .

Using above i need to make 01-APR-2015 to 31-DEC-2015 as a short year , however it is not allowing me to modify this calendar  & giving me an error