Help passing shared variable from sub report to Main report

Hi

I have a subreport that contains a field with a Y or N value

I want to pass this value to the main report (so that I can use it in a formula to be used as a condition in the header), however I dont seem to be able to get the value returned in the main report, here is what I have done so far -:

I have created a formula {@FullyPaid} in the subreport and placed this in the header of the subreport -:

WhilePrintingRecords;

Shared Stringvar FullyPaid:= {V_CONF_CRITERIA.FULLPAYMENT};

FullyPaid;

I have created a formula {@FullyPaid} in the main report and placed this in the header of the main report (to check the value is returned before applying it to my main condition formula)  :-

WhilePrintingRecords;

Shared StringVar FullyPaid;

FullyPaid;

My subreport is in the header (GH7)

My new formula {@FullyPaid} is in a subsection of this header (GH7a)