[graph-tool] Posterior entropy approximations = 0?

Hello, I am sampling the posterior distribution in order to carry out some model selection (much like outlined in the cookbook). Interestingly both the Bethe as well as the mean field approximations of the posterior entropy appear to be returning an answer of 0.0. I was thus after some opinions: Are there cases where I might reasonably expect this to be the correct answer/how would people check that it is not simply being caused by the approximations not being applicable to my data set? Thank you for any help in advance! -- Sent from: http://main-discussion-list-for-the-graph-tool-project.982480.n3.nabble.com/