When all the lines are nines, it means

There appears a flight of dragons without heads.

Good fortune.

When all the lines are nines, it means that the whole hexagram is in motion and changes into the hexagram K'un, The Receptive, whose character is devotion. The strength of the Creative and the mildness of the Receptive unite. Strength is indicated by the flight of dragons, mildness by the fact that their heads are hidden. This means that mildness in action joined to strength of decision brings good fortune.