Trailing Twelve Month Question and Point in Time

[#1]

In my model, I am trying to display TTM for EBITDA.  I currently have  Sep 2013 selected and when I create an object and have the following expression in the the text box, I get the correct results. The results I get is sum of EBITDA for the current month and the last 11months.

=sum({<Scenario={'ACTUAL'} ,$(sTTM)>}[EBITDA])

However, when I place this same expression in a chart, with Month as a dimension,  I am only getting EBITDA for the current month.  I actually would like to get the EBITDA for the current month and the last 11 months.  

Here is my expression for the point in time for sTTM  :

sTTM=

[%Month Overall TD]={">=$(=max([%Month Overall TD])-11)"},[Fiscal Year]= ,

[MMR Version] =, Year=, Month =, [Calendar Date] =, [Fiscal Date] = ,[Month In Quarter] =, [Month Number], Quarter=, [Quarter-Year]=,

[%CALENDAR_LINK TD] = {"<=$(=max([%CALENDAR_LINK TD]))"}

Any thoughts or suggestion on how I could accomplished in a chart with my current expression and point in time expression.