Recently Okular's internal version changed and so did the requirement for Okular by Calligra.
Okular is now set to 0.99.0 for the stable Applications/16.12 branch and Calligra wants 0.99.60. How before these versions changed I had a version of Calligra master (due to become 3.0.0 shortly) which compiled fine with Okular from Applications/16.12 http://build.neon.kde.org/job/xenial_stable_calligra_calligra_bin_amd64/1/ It would be a shame if Calligra released without a version of Okular that it worked with also being released. Does Calligra work with Okular from Applications/16.12 ? Jonathan