I am trying to write check method in process builder. But couldn't manage run process builder smoothly. This is what I want and what I tried
if (Account is new OR AA_field changed) AND (B_field is null))
Then run the action
OR(ISNEW(), ISCHANGED([Account].A_field), AND(ISNULL([Account].B_field)))
But I am doing it wrongly. How can I achieve this?