Scripts

The script doesn't work:
if GetDifficulty() == DIFFICULTY_EASY then
AddObjectCreatures ( "townhero",78,5 );
AddObjectCreatures ( "townhero",142,7 );
GiveExp( "Ferigl",17500 );
end;

if GetDifficulty() == DIFFICULTY_NORMAL then
AddObjectCreatures ( "townhero",78,7 );
AddObjectCreatures ( "townhero",142,7 );
GiveExp ( "Ferigl",12200 );
end;

if GetDifficulty() == DIFFICULTY_HARD then
AddObjectCreatures ( "townhero",78,6 );
AddObjectCreatures ( "townhero",142,6 );
GiveExp( "Ferigl",10000 );
end;

if GetDifficulty() == DIFFICULTY_HEROIC then
AddObjectCreatures ( "townhero",78,4 );
AddObjectCreatures ( "townhero",82,2 );;
GiveExp( "Ferigl",6200 );
end;
Question: what is the error?