Here's why:
* Schwa sound: The schwa sound is a very short, unstressed vowel sound represented by the symbol "ə". It's often found in unstressed syllables.
* "Again" pronunciation: The word "again" has two syllables: "a-gain". The first syllable is stressed, and the vowel sound in "a" is a clear "a" sound (like in the word "cat"). The second syllable, "gain", is also stressed, and the vowel sound is a long "a" sound (like in the word "say").
Therefore, "again" doesn't have any unstressed syllables with a schwa sound.