Power Pivot Row = Month , Year = Column comparison

Hi, this relates to power pivot; I have a year on year growth measure staring with sply;

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and this works if I have Year and month in rows but if I put year in columns so icols = 2011 , 2012
and rows = Months , "total Sales" measure will give a correct result for each year but if I put a sply or growth measure in it fails,
I have tried to show the result I would like by using two total measure to illustrate what I am looking for,

I have attached a work book withe the examples , I cant' see why it does not work? The error message say DATEADD only works with contiguous date selection,
but I get the same message when I try and use the second "totals" measure which does not use dateadd?


Richard.