Vauxall Astra 1999, 1600cc, wont start after head gasket change?

Engine turns , fuel is there, have spark, wont fire up. When removed head number 1 cyl at TDC on ignition stroke, marked crankshaft in alighn with pointer, engine has not been turned, camshaft still in align. Only possible thing i can think of is gasket wrong way round but i'm certain its right, There is no coughing, spluttering, nothing just turns.