The following question was asked via email support:

Do you have insights why certain hyperlink networks do not have a value for betweenness centrality or closeness centrality? 

Answer: 

This is because the network in question is not a single component i.e. there must be isolated nodes or else perhaps clusters of nodes that are disconnected from the main graph.

In such a situation, closeness centrality is not defined and VOSON will not compute it (or betweenness centrality).

The only way to get VOSON to compute these measures for your network would be to create a subnetwork (via Crosstabs->Composition) of the nodes in the main component. You can then save it as a subnetwork and when you re-open it, the centrality measures should be there.