When I play the Macedon, and tried to besiege some settlements. I have conquered three provinces.

But when I want to attack the next city and put my mouse over that city, it will not change to attack icon. So I can only click the city to view details, but cannot besiege it. Dont know why. Already in war with that city and eliminate all its armies.

one more detail: there seems to be two agents stand on the city, then I can't attack the city.