You have to be careful about expecting tax decreases when your property value goes down.
Existing levies are, at the time they were last voted upon, certified for a specific dollar amount for the term of the levy. Because the entity is 'certified' to receive that specific amount of money, you will pay a set amount based upon the value of your property at the time the levy was passed. So, for those specific levies that are in existence, you will not see a reduction in your taxes.
But, when they are up for renewal, they will be certified at that time based upon the current property value and, if your value has decreased, the amount you pay for those levies will as well.
It's a strange quirk that results in what is known as the 'effective' millage.
Other entities, like the city and the county, get a portion of your property taxes and those amounts should go down if your property tax goes down.
I know - complicated and hard to explain...let me know if you have further questions.