How to make a make a door that need two keys to unlock it?

[Raymond]

Now the it doesn't have effects, my .hps is like this:

Code: (Select All)

void Onstart()
{
AddUseItemCallback("UseKey1", "prisonkeylight_1", "mansion_3", "KeyCounter", true);
SetLocalVarInt("KeysUsed", 0);
AddUseItemCallback("UseKey2", "prisonkeydark_1", "mansion_3", "KeyCounter", true);
}

void KeyCounter(string &in asItem, string &in asEntity)
{
AddLocalVarInt("KeysUsed", 1);
if(GetLocalVarInt("KeysUsed")==2)
SetSwingDoorLocked("mansion_3", false, true);
PlaySoundAtEntity("", "unlock_door", "mansion_3", 0, false);
}

I use the first key and it says: "Cannot Use This Item Away!" Could someone please help?