the red chakra is not his, he just borrow it from Kyuubi and guess what?? Kyuubi is in the real Naruto, so the clone will be cut off of their supply of red chakara.

think as this Naruto is a lightbulb and Kyuubi is a battery, electric from the battery flow directly to the lightbulb but if u dublicate only the lightbulb, those lightbulbs does not have connections to the source, therefore they are unable to glow