In the book that I'm now reading, it says that the sentence
(1) "Only two of us had some experience in sailing"
is ungrammatical, because 'only' has negative meaning, so the positive polarity item 'some' cannot be positioned in this sentence.
(2) "Only two of us had any experience in sailing"
is the correct sentence according to this book.
However, I am now really confused by these two sentences. Do they have the same meaning, and also, is it right to say the sentence (1) is strictly ungrammatical?