So, a trick I often use for a player detector is a command block with the command /testfor @p[r=*] pointing into a comparator, followed by another command block with a command of my choosing such as /tp @e[r=15] 400 75 49
But it seems that the /testfor command no longer is there.
I've taken some time looking though the auto-fill options, testing them to see what works, but I can't find a work-around. That said, I chose to come to you guys.
Your test for looks fine. The only problem I can see is with the @e on the second command. You would want to use @a or @p for players.
But i recommend condensing this down to one command block.
tp @p[r=14] 400 75 49
If you need more than just one action, you can use chain commands instead of a comparator. For this you put multiple command blocks right next to each other. Change everything after the first command block to chain, conditional, always on. All commands will execute one after another automatically.