Business networking communities online are just like any other community, I'm never sure why people think they should behave differently online.
The mistake I see people making, is to head straight for the Classified Ads section and expect people to take notice of them. You HAVE to engage, you HAVE to involve yourself in the community before people will be interested in you and your business.
Consider this for a second, you arrive at a breakfast meet or other networking event where you don't know anyone. Immediately you stand on a chair and start broadcasting your message and your current special offer. What do you think people would think of you? Yet people do exactly that here.
Spend some time getting to know the other people in the community. Find out about their businesses, see if you have knowledge or advice that might help. By doing so, you will also get an understanding of their business, which might help you to pass business their way in the future and will definitely help you to understand how your products and services might help them.
First assemble a crowd of people who know and like you. In fact, why not just do that, business might just start flowing to you without you ever asking for it.