A big fear preventing knowledge sharing is the fear of being seen as not an expert.
Many people, in the knowledge economy, are hired to be experts within their particular field. If they ask a question publicly, they’re admitting they don’t know something. Ask too many questions and they begin to look rather dim – at least they fear they do.
If you don’t have people asking for information, this might be the reason.
There are two options here. One is to change the culture to celebrate those that learn something new. That requires stories of people that became experts by constantly asking questions of the community. One is to champion those that want to learn and subtly mock the scared ‘experts’. Not easy.
The second option is easy. Provide an option for a registered user to hide their name from the question. They, and other members, still get the value of the answer – but they don’t have to have their name attached to it. Neither is an easy option, both are do-able.