I am having similar issues.
I have delared a shared variable in the subreport brought it forward into the main report but the variable is one entry behind.
So if the value in the subreport for Entry 1 is 'Yes' and then Entry two is 'No'
Then when it is shown in the Main report the first entry always shows up blank and the second entry displays 'Yes' and 'No' would be displayed for entry 3 etc.
I have yet to work out a solution to this problem.
The worst thing is if our developers created the database correctly I wouldn't need a subreport!