I think it is likely that the report is just very slightly too large to fit on one page, when printed. So increase the margins on the report, to allow for this.
There are slight differences in how a report prints to the screen, compared to various printers.
Furthermore, the report prints to the screen based on a printer specified by the report, or the default printer if none is specified (or the specified printer is unavailable).
In short, it is amazing it even works some of the time.
To improve your chances of success, use printers that don't require big margins (laser printers generally). Inkjet printers usually have at least one margin that is quite large - depending on the brand, this is usually the top or the bottom margin. If your report is being printed on an inkjet, try to leave big margins on BOTH the top and bottom (unless you know only one type of inkjet printer will be used, and thus know where the big margin is needed).
Dot matrix printers - frankly, I haven't had to produce a report for dot matrix in many years. So, if your problem is with a dot matrix, be sure to mention that in any response, because there must be someone out there who still uses them and can help.