unable to get pivot table to display Running Total In correctly across a year end

Hi,
I attached an example (with random data) of the problem I fail to resolve.
The Data Sheet has data sorted by dates running from 1 Jul 17 to 28 Feb 18.
In the Cash Flow Projection sheet I wish to display accumulated estimated outflows compared to accumulated estimated inflows over the relevant period of 8 months in a simple line chart. For this I used "Running Total In" on the "Show Values As" tab under the "Value Field Settings" to give me the accumulating data values.
I get it to display correctly from Jul to Dec, but it starts calculating anew from Jan to Feb. The chart shows what I mean.
I have fiddled around, but cannot seem to get it right. One option was to remove Years from the Axis, but then Jan & Feb 18 shows before Jul to Dec 17 on the chart that confuses a viewer.
Could some kind person please point me to what I fail to see/do?
Thank you kindly.
A

Jete,
Much obliged. Things seem so easy now that the solution is in front of me.
Thanks also for other (unintended) tip I got from you i.e. simple, but practical naming protocols for headings on top of the helper columns, and also a simple and clean formatted chart.
What is old hat to experienced hands, are often eye openers for the uninitiated.
You kindness and effort is truly appreciated.
I will mark this thread as solved.
Kind regards.
B

Maybe such a proposal?