You can tell from your results whether you've made a syntax error or not. Extract returns a stream of responses or gives you an error message, as follows. In such cases, refer to this guide to check your syntax.
OK (? for help): extract -f "Eva Turner"
extract: no such conference 'Turner'
OK (? for help): !extract -f "Eva Turner"
Usage: extract [-aeEFgGhHiLmnopPrRtUwX] [-bs when] [-BS file] -du user] [-fT string] conferences [topics [responses ...]]
The command above failed because no conference name was provided, only a text string.
You must examine your output for more subtle errors, such as giving incorrect date and/or time boundaries in your command.
That's the end of the tour! Go back to the Extract Home Page.