Vinay,
Please see the SAP Help (http://goo.gl/HI2bwe). A miscreant transport (or an activation in a development environment) will allow the table to be activated (check _SYS_REPO.ACTIVE_OBJECT) but this object is inconsistent (e.g., the design time specifications were not wholly implemented.in the run time object.) Check your Studio Job Log for the activation (or import logs in the case of transport errors.), Correct and re-activate (re-transport.)
Good luck,
Robert