Who is responsible for condo association fees on foreclosed units?

Our Ohio condo association has a foreclosed unit that sold at auction on 2/21. The bank was the buyer. We initiated billing for condo association fees and they made one payment, but it was short of the amount owed. The bank then transfered control to Fannie Mae. A Fannie Mae representative contacted us for billing info and told us we would receive timely payments every month effective 4/23. We provided the data and they forwarded it to their agent, which turns out to be the bank that was initially in control.

We have still not received any other payments and it is currently 3 months behind. The property was listed and has sold. We don’t know a closing date yet. We are concerned that once the new buyer closes we will never see our past monies from the bank or Fannie Mae. Can we do anything to bind the closing pending full payment of the monies owed to us. We are already 18 months short on this property.