Could Lights be seen UNDER the Invisibility Cloak???

Ok, I know this sounds stupid, BUT in Harry Potter seven (That will be Deathly Hallows) >!Harry said "Nox" for turning off the wand light AFTER climbing into the Invisibility Cloak in Chapter 32 (Elder Wand) !< If it COULD be seen under the Cloak, then makes sense why does Harry have to Nox it but then the Cloak is supposed to turn everything inside it invisible. If it COULD NOT be seen then why turn off the lights??? Could anybody please tell me about this?
(Sorry, my english is bad)