You should check the page source code (if the form is submitted using a PostBack) or the CallBack response body to see whether the event is in the events list.
You can use Chrome/IE Developer Tools or Firebug to watch the network activity.
I believe the event isn't visible (and you won't be able to find it in the events list) because your WHERE section in the SELECT command is too restrictive.
It may be be also affected by the way you store the event start and end DateTime values. Zero-duration events (with the same start and end) are fully supported in the latest release so you should. If you are using an older release you should consider switching to the latest one or store the event end as start + 1 day (or at least 1 minute).
Please let me know if it didn't help.