You need to be ruthless. Don’t think twice about abandoning community elements that aren’t working.
The temptation is always to push harder. You know, send another e-mail reminder about that unused feature, create another piece of content to attract an audience that isn’t joining in droves, have some incentives to encourage participation in a particular activity.
Don’t ever do this.
Don’t waste time on what isn’t working. Don’t annoy your community trying to change thir behaviour. Changing behaviour is hard. Follow the Heath brother’s advice and focus on the bright spots.
What elements of your community are working? Where is your audience talking to each other? Are they only using a limited feature of your site? Are they talking elsewhere? Do they only talk about specific topics? Is only a specific niche of your audience joining the community?
Abandon the waste and micro-focus your efforts on making the successful elements more successful. Focus your efforts on the community elements you can turn into a thriving community. It’s far easier and more effective than trying to change behaviours.
(and if nothing is working, that’s probably a good indicator too!)