Oh, Jenna Elfman. When the premise of your sitcom revolves around the fact that your character Billie, a 37-year-old film critic, is impregnated by a one-night stand with a younger man, the time may have come to stop acting like a girlish twenty-something.

Even the occasional funny lines in the painfully expository pilot are lost as Elfman shakes her head of bouncy blonde curls (did she scalp Christina Applegate after Samantha Who? was canceled?) and gasps her dialogue with “Gee whiz!” earnestness and a pronounced lisp. Grant Show, as Billie’s boss and sometimes boyfriend, looks fantastic and deserves better. Likewise for Extras and Ugly Betty alum Ashley Jensen, who has ratcheted up her hard-drinking Ugly Betty character to almost blinding levels.

But worst of all is Billie’s relationship with her younger lover Zach (Jon Foster). Adamant about being a part of his unborn child’s life, Zach moves in with Billie to what should be comic misunderstandings. But Billie insists on maintaining a platonic relationship, which is just frustrating. There’s young, hottie Zach, lying naked in Billie’s bed, and she orders him to leave? She’s already pregnant, what does she have to lose? There’s also the innate sordidness of the premise, one in which Billie’s irresponsibility regarding condom use results in pregnancy, and not an STD.

There’s still hope for the series (I found myself laughing once or twice), especially when allowances are made for a pilot that had so much ground to cover in establishing the characters and plots. But Billie seems to be a sitcom version of Carrie Bradshaw, and whether or not Accidentally on Purpose will thrive or implode depends greatly on how willing the writers are to find the individuality in their wan set-ups. The signs are there (Billie’s art includes posters for Gilda and An American Werewolf in London), but the perky Elfman seems bent on keeping things as upbeat and sunshine-y as possible.