Can't really say how you need to do your link as I don't know you what you are trying to accomplish or your data structures. Just trying to make sure you understand what is happening in the main and sub report linking process.
To clarify the one value thing here are examples...
say you are linking on customer id. you are only passing one customer id to the subreport each time the sub report runs inside the main report. So if you place the suberport in the main report's report header it only runs once and will only pass the first customer id it finds (the first row of data).
if on the other hand, in the main report you have a group using the cusomer id and you place the sub report in the group header or group footer it will run the sub report once per customer id (once per instance of your main report group) and 1 customer id each time it runs.
Hope that helps rather than making it more confusing.
Edited by DBlank - 25 Aug 2011 at 7:27am