It's kvetch, kvetch, kvetch on the stage of the American Theater at L'Enfant Plaza these days, where the New Playwrights' Theater is presenting the premiere of Mark Stein's "Breaking the Sweet Glass."

The Posinsky family has its problems. Dad is broke, Mom loathes him, 31-year-old Irene is about to be married primarily because she's pregnant, and younger sister Rachel is bedeviled by the world's entirely justified rejection of her musical skills. Of all these problems, it is strongly hinted that the playwright feels Rachel's is the worst.

The clan spends most of its time in grim lamentations, endlessly exchanging accusatory looks and gripes with each other. It's hard to believe these people were ever related in the first place.

There are two other characters: an overbearing rabbi and Irene's flustered fiance, who is sensibly less than thrilled about the prospects for marital bliss within the Posinsky family.

Occasionally the direct moaning and groaning is interrupted by sorrowful memories recalled in day-dreaming sequences. In one of these scenes, the rabbi is assigned the lines of one of Irene's old beaus. Perhaps this is an attempt to make the Jewishness of the Posinskys more central to their dilemma than it otherwise appears. It's hard to tell.

The New Playwrights' Theater does not seem comfortable in its temporary home at the American Theater. Harry Bagdasian's production is poorly focused. It's not uncommon for one set of characters to be pounding away at each other in one corner of the set while another set of characters mimes its own confrontation in another corner of the set. Sometimes the silent conversationalists are even more prominently visible than the ones with the playwrights' dialogue. Nothing could be more distracting.

Miscasting abounds. The parents don't look much older than their older daughter. Not a single performance appears tightly conceived. A tired play may tax an actor's resources, but a production as tired as this one makes it difficult for the playwright to see if there's anything salvageable.