Mirror Image is on the GCD. What happens when you click the macro is that it will execute up to Mirror Image, then stop, because it has the GCD. In order to execute the rest of them, you'd have to click them again.The macro does work just fine, though. Also, I don't understand why some people prefer to use alter time when there's 6 secs left of icy veins, instead of just at the start. You still extend the duration by 6 seconds, no matter what. So, I usually use that macro whenever Tempus Repit procs.
And as Komma said above (though I think he mistype IV as AT), but casting IV first, it increases your chance to proc PBOI (since PBOI procs on hit, and IV makes your spells hit 3 times).