Different Cumulative Totals on same visual

Hi,

I have two query tables, one that shows sales targets by sector, by Month and a separate table that shows potential sales opportunities by sector, by month...

I have created a TotalYTD measure which when shown asa individual visuals work perfectly well & I can either have it ads a data table or a line/bar chart & they accumulate nicely.

However, I want to show both numbers on thesame visual (Bar & line graph) so that I can show the potential sales opportunities (as a stacked bar) & see how far away they are from the cumulative total (as a line)

When I do this, the potential sales accumulate as they should, but the target remains as the individual month values (ie they dont cumulate)

even if I use the same date column to drive my TOTALYTD calculation it has the same result..

any pointers would be great :o)