Ultimately, you will be responsible for the success or failure of any event that you are planning and there must be a willingness to be accountable for any activities that occur and be willing to accept the praise when it is warranted and the criticism when it is necessary. There cannot be a disconnect from the situation, when something goes wrong, which then precipitates you blaming others for what is going wrong.
Responsibility is yours and you need to act accordingly and be accountable for whatever takes place. This sometimes leads to individuals attempting to do many tasks themselves so as to ensure that the tasks are done. Trying to take over everything, solves little, and only helps to exhaust the individual event planner and does nothing to build the abilities of those around you.
They need to do their part as you cannot do everything yourself to make an event work. Inspire leadership by working through others means also taking the responsibility for what they do. This requires that you build there abilities over time so that they can be competent and confident when they are asked to take on event responsibilities.