That is a big upgrade jump. You might want to consider upgrading through the intermediate versions. This has helped some people making version updates in the past.
You can get trial versions (that will allow you to update your file format) of previous versions at the bottom of the download page.
Otherwise, you will have to print the account to PDF in the old software, look at the pdf while the account is open in the new and compare at various dates till you find what is wrong. Probably is is moving data between accounts.