Markua has not been fully implemented yet, so you may be trying to do something we haven't built yet.

You'll find a list of things not yet implemented here: https://leanpub.com/markua/read#leanpub-authors

If you're trying to do something that is not on that list, then you may have found a bug. If that is the case, please email hello@leanpub.com and let us know what you were trying to do that did not work, and we will look into it.