Walls and Ceilings - please help? historical courthouse cracking apart!

We are drywall finishers and painters and took on this plaster job at the court house. It turns out to be a bigger job then we imagined. One room has 3 four foot holes down to the concrete blocks and hairline cracks the lenght of wall on each wall, some walls have cracks on top and bottom. window sills are plaster and chunked off here and there. we bedded in the giants with gypsum plaster witha little alum sprinkled on to harden on top of the glue brushed on the blocks., we covered with a finish coat of moulding plaster and lime and also used this formula for the deeper cracks, then we just used finish coat to fill surface cracks and feathering. the next day most of the finish coat had flaked , cracked and shattered and is now on the floor. whats left looks like antiqueing or old peeling paint. what the heck did we do wrong aside from taking the job in the first place? And where is the lathing? there seems to be only lathing around corners of windows. please, any wisdom from experience would be greatly appreciated