If you have no Document CALs at all, or you ran out of available document CALs, the Document CAL tab will not appear for documents that have no CALs reserved.
Buy or free up some, and the tab will show up again. For an overview of the CAL types and the numbers, see QMC->System->Licenses->QlikView Server->General. The grey title bars will show you how many of each you have in license, and how many are still available.
Best,
Peter
