Business leaders say protectionism is impeding efforts by firms to invest in the region.
Asian countries continue to flood markets blamed on tax exemption by some partner states.
Rwandan President accuses Uganda of erecting non-tariff barriers to trade in the region.
Ethiopia last week took the agreement through Parliament, becoming the 21st country to do so.
Tewolde GebreMariam strikes a conciliatory tone towards the American plane maker.