hi Victoria,
was there a particular sql query that you used to get the results from access? if so, create a new report, and instead of adding your tables to the report press Add Command and then paste this sql syntax into the command object and run the report off of that.
joins between tables can be problematic for bringing back all required records, especially if they are equal joins. another possiblity of what could be happening is that there is a Record Selection formula / filter that eliminates the records that you are looking for.
-jamie