Hi, Nancy,
Can you describe in general how the subreport is defined, and what section of the report it resides?
There are a handful of reasons this could be happening. One possibility is that the subreport is part of a group/section where a pagebreak is defined ('newpage before/newpage after').
For both the subreport and the group/section to which it belongs, do a right-click and check out the formatting options to see if a pagebreak is defined.
Kevin