Why is there still no official recognition of private property rights in space?  

       When there is finally adequate recognition of private property rights in space, won´t there be a much greater incentive to invest in space-related ventures?   Mining, colonizing, and tourism center development, some of the major justifications for investing in commercial space activities, are considerably less likely to occur there without such official recognition.         

       Nations are clearly prohibited from appropriating land on celestial bodies in outer space.   However, can the same be said for private individuals or completely nongovernmental entities?

Article II of the 1967 Outer Space Treaty of the United Nations (ratified by around 100 member countries) states that:

"Outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means."  

Where does it say that private appropriation is banned, though?   

      Subsequently, drafters of the 1979 Agreement Governing the Activities of States on the Moon and Other Celestial Bodies attempted to close off this apparent loophole which favors private appropriation.  The "Moon Treaty", as it is otherwise called, declares the Moon as the "common heritage of mankind" and essentially creates an engine of redistribution that would give all nations a share of the wealth produced from activities in space.   Nevertheless, only 8 nations (none of which are major spacefaring ones) ratified it, and  merely another four are signatories to it.    Along with the U.S.A, even the Soviet Union and China refused to sign it!   Many analysts interpret this overwhelming lack of international acceptance as a popular rejection of the elimination of private property rights in space.   This rejection took place even before the thawing of the Cold War, too.   

     Are governments doing enough today to reassure investors and entrepreneurs that their claims, or potential claims, to property in space will get sufficient respect though?

Here is a representative list of websites regarding the
movement to solidify private property rights' recognition in space: