It's not only that star AnnaSophia Robb's tangled mass of blonde curls can't disguise the fact that she's not going to grow up to look remotely like Sarah Jessica Parker (though I'd argue that being a less conventional beauty than Robb likely formed part of the original character's personality).
Or that the teens and twentysomethings in the CW's target demo probably haven't had the relationship with Carrie and "Sex and the City" that their mothers or older sisters might have. Or if they had, that they're likely too advanced to want to repeat high school with her.
It's that the Carrie we met on HBO in 1998, while charming, was a little damaged. That's interesting in an adult character, but in an adolescent, it feels more like a problem that needs solving.
Based loosely on two young-adult books by Candace Bushnell, whose work also inspired "Sex and the City," "The Carrie Diaries" deviates from Carrie's sketchy backstory in the HBO series, giving her a widowed father (Matt Letscher) instead of an absent one and endowing her with a younger sister, Dorrit (Stefania Owen), who by the third episode had become my favorite character in the show.
Mr. Big is decades away, but there's a rich, slightly withholding kid named Sebastian (Austin Butler) tugging at our heroine's heartstrings. The girl already has a type.
The device that gives the 16-year-old Carrie a secret life in Manhattan isn't even as likely as the one employed in ABC Family's "Jane By Design" (a show I kind of miss, where a high school student masqueraded as an adult in the fashion industry).
"Diaries' " sexual frankness, though, leaves "Jane" in the dust.
Not that that's necessarily a bad thing. When one character (not Carrie) describes her first sexual experience in terms more graphic than glowing, it felt like a genuine moment.
A few more of those, and I might not worry so much about how long it'll take for this Carrie to grow up.
On Twitter: @elgray