Check the HTML source of the result output for any error messages (eg. "Query would require post-processing"). Make sure you've run gw -index. Also, what is the version number of Vortex that you are running (run texis -version from the command line and report the date)?
There is an issue in Vortex versions prior to Oct. 25, 1999 with phrase searches sometimes not returning the correct number of rows when the query has other terms as well. The workaround (as you've accidentally discovered) is to add a NOT set (minus) for a term that doesn't exist.
Thanks Kai.
No, there aren't any error messages in the HTML source of the result output.
gw -index has already been run.
The version number of Vortex is:
Commercial Webinator Version 2.6.927146786 of May 19, 1999 (i686-unknown-linux1.2.13)
We'll need your DR number (from the CD or invoice).
Also, I see that you're running a version for Linux 1.x kernels.
Do you need that or do you actually have a 2.x kernel so that you can run newer programs? uname -a will tell you what kernel you're running.