Forum:Protective Charms in Deathly Hallows

In the battle over Little Whinging, with the decoy Harry's, Harry falls to safety within the Tonks' boundaries. Voldemort is unable to follow because of the protective spells and enchantments. This might seem silly but why wasn't Voldemort able to go through? Both him and Harry were traveling by untraceable means. I suppose it may be that the charms would not allow anyone with a dark mark through, just like the Death Eaters can set up something to recognize the Dark Mark. Maybe the spells were set up to recognize certain people? The answer might be right in my face and I'm just not getting it. However, I'm really interested in other peoples opinions.....