If the ref forgets to warn?

[MrRottweiler]

The rulebook should state that the players themselves should be aware of it regardless of a warning. It only happens when they miss everything so they know the score during the third attempt and it would be bad etiquette to try to get out of it with the excuse of no warning. I suspect most players would be confused enough to query it with the ref before the shot.

[Londonlad147]

it would be bad etiquette to try to get out of it with the excuse of no warning

Sometimes, though, it is not clear cut whether the striker has central fuill ball contact available to him (a requirement for the awarding of a frame after three misses). It can be a very close call on occasions and if a warning is not given after two misses the striker and/or the non-striker might believe that the referee does not consider there to be central fuill ball contact available, so you really can't put the onus on the players.