I'd probably second Rob - as a manager you can do as much as possible to give employees the opportunity to undertake professional development but it's down to the individual to take it up. For my part I'm keen to encourage more involvement with community events, but because they're often free or cheap some people don't see them to have as much value.

We can do some things to help such as: give time off in lieu for weekend/evening events, pay travel expenses, allow time in work hours for preparation.