Go to Events in your form-level control panel and be sure the event in question is toggled to the On position.
Once you check that, Edit the event and be sure that all of the Packages are also toggled to the On position, as shown below.
If everything is turned on, check the event dates in the general event info area by clicking Edit next the name of the event, then checking the Event Settings area. You want to be sure the start and end dates are the dates of the actual event NOT the registration dates. The system does turn the event off once the start date is reached.