Looking at the source for 2.5.4 and http://dbunit.sourceforge.net/datatypes.html
The documentation shows that a file load instruction is [FILE /path/to/file] but the source code on 2.5.4 is using the extra text following the end bracket instead of split[1] for the filename which means the documentation should read:
[FILE]/path/to/file (no spaces, important)
Since fixing the code would break backwards compatibility, suggest fixing the documentation.
Merge request #46 fixes the documentation. Thank you for reporting this mistake.