display current selection and 12 months before current selection in bar chart

[#1]

i am calculating the both current selection and 12 months in bar chart . in button object wrote this code like if(vtogle_something='last',12months,current selection)

i m using this code to write the expression in bar chart  like (if vtogle_some='last',

i don't next  and also using the condition(expression like rate%)

count( if(op_status='won',op_status))/count(op_status) to display the bar chart corresponding clicks in one button object plz tell me the working expression........plz........urgent 

[#2]

Couldn't understand your requirement. Can you give some sample data or screenshot and what are you trying to achieve ?