how to make an enemy appear after a trigger?

[Crypto]

I am also new at scripting.So i have done this much

////////////////////////////
// Run when entering map
void OnEnter()
{
AddUseItemCallback("", "key_tomb_1", "castle_2", "KeyOnDoor", true);
}

void KeyOnDoor(string &in asItem, string &in asEntity)
{
SetSwingDoorLocked("castle_2", false, true);
PlaySoundAtEntity("", "unlock_door.snt", "castle_2", 0.0f, true);
void OnStart()
{
AddEntityCollideCallback("Player" , "ScriptArea_1" , "MonsterFunc1" , true , 1);
}
void MonsterFunc1(string &in asParent , string &in asChild , int alState)
{
SetEntityActive("servant_grunt" , true);
}

But this comes up when i launch the map
: FATAL ERROR: Could not load script file
'custom_stories/maps/custom_storiest/maps/maps/MansionEscape.hps
'!
main (19,2) : ERR : Unexpected end of file. anyone has idea whats wrong with this ?