/testfor command

I try to make a teleportation systeme. When we are are on XYZ we are tp to a point ,but I try to do a testfor command to detect the player that he is in range for the tp but the testfor command does not work.... I search on the wiki and some forums to find what is going on, but the only thing I found is how to use the command. So I use it correctly but it's said me that the UUID is not correct (See the picture). I Think that this is a bug... And also i ask some people that they are good with command block and don't have any idea why...