Dynamically Read time period in MDX for member formula

Experts,

I have a requirement in member formula where I need to read a value of account corresponding to December month. As the member formula will run for all the time periods, I need to read December month for every year.

For e.g

For January month of 2015

ACC1 =ACC2,[TIME].[2015.JAN]/ACC3,[2015.DEC]

For January month of 2016

ACC1 =ACC2,[TIME].[2016.JAN]/ACC3,[2016.DEC]

I am not specifying the time member in numerator as it has to run for all time periods as below but I am not able to derive the Dec month of current year dynamically.

ACC1 =ACC2/ACC3,[2015.DEC]

ACC1 =ACC2/ACC3,[2016.DEC]

I tried   this   ACC1=ACC2/ACC3,STRTOMEMBER("[TIME].[" + [TIME].CURRENTMEMBER.PROPERTIES("YEAR") +".DEC"+ "]"     but its not working.

Any suggestions and help will be appreciated.

Regards

Nikhil

Message was edited by: Nikhil Anand