Error Message, doesn't specify what problem is

[Rokotain]

Problem 3:

Make a script area around the door, go into the "area" tab on the right and fill in the PlayerLookAtCallback box with "kitchenlookat" and make sure "PlayerLookAtCallbackAutoRemove" is checked, then go into your .hps and anywhere in it, put this, changing caps with your info:

//__________________________

void kitchenlookat(string &in asEntity, int alState)
{
SetMessage("MESSAGE_CATEGORY", "MESSAGE_ENTRY", 4);
}

Sorry if this is a really nooby question : p
But what should I put in the message category? I tried something similar once, but just got error.
Would you please post an example^^?