Make it personal. Express passion about your organization. Challenge them to get involved. People need a reason to be involved or an issue to force them to get up and do something. Get their input and make them a part of the product and event.
Every person has different assets and talents to bring to an organization.
Sometimes a person is only interested in a certain facet of an organization's activities. More collaboration among community leaders, business and industry. Let your resources know you appreciate and depend on them. Ask for funds from business and industry, underwriting of events. Tell them what you're doing and why you need the money.