I started dropping formulas, and found each one DID return a result:

it all depends on what the related formulas are doing. Also keep in mind that a sub report runs (fetches data seperately, evaluates, creates display, etc) seperately for each instance it appears in your report, so if you place it the detail section and you have 100 rows of data in the main report it is like running 101 reports at the saem time with 101 distinct dat fetches to the server, etc.

Would it be correct to say that if I needed to do calculations on my subreport based on formulas on my Main report, that I need to create shared numberbvar(s) for EACH formula on the Main report that is involved in said calculation?

ok, thanks much