Here are a few things to look for:
Be sure your form fits within the margins specified in
File > Page Setup. Add headers and footers when
calculating this.
If you have added a page break, make sure there is nothing
below it. In general, try to use grouping rather than
page breaks to do something such as having each record
start on a new page.
If the margins appear to be in order, drag the right edge
of the report to the left, as if trying to cut off part of
the report, then let go. It will snap back to excatly
where it needs to be to accomodate the text boxes, etc. on
the report. Repeat with the bottom of the report.
