Silverlight- KB2668562 did not install per windows update error code 80070643

was notified that Windows Updartes were available.  Accepted and update proceeded. All updates installed no problem except  KB2668562 .  Got notification that error code 80070643 -  (This update is for Silverlight what ever that is ???) 

 ran MS FIX program -  was told that a problem was detected and fixed.  Went back and checked update history -  same result - did not install.