  Measurements of the pp-->ppK+K- reaction, performed near the kinematical
threshold with the experiment COSY-11 at the Cooler Synchrotron COSY, reveal a
significant discrepancy between obtained excitation function and theoretical
expectations neglecting interactions of kaons. In order to deepen our knowledge
about the low energy dynamics of the ppKK system we investigated population of
events for the pp-->ppK+K- reaction as a function of the invariant masses of
two particle subsystems. Based for the first time on the low-energy K+K-
invariant mass distributions and the generalized Dalitz plot analysis, we
estimated the scattering length for the K+K- interaction.
