Hi Andy
Unfortunately your last post has made things more confusing as to what's happening

It will all make perfect sense to you as it's your project and you know exactly what happens re the flow of things, but for others (well, for others certaily read me!!) who have no knowledge of your db we don't have that luxury.
I'm not sure now with your latest post whether the report get's it's various values by referencing controls on the form (as you say it doesn't have a recordsource) and then the calculations are perfomed by the report, or there's something else happening.
I'd still suggest that maybe you could perform whatever calculation(s) you need via the Function route, but again without a lot more detailed info from you it's not really possible to hazard a guess.
Perhaps you could post in more detail exactly what happens and where values are coming from/calculations being perfomed ?