If it isn't one problem, it's another for local socialites. Last night, of all things, the bus driver carting around a whole truckload of them got lost on his way to a Washington Ballet benefit at the Ecuadorean Embassy.

"Oh, for heaven's sake," said Luna Diamond when she heard. She's on the Washington Ballet Women's Committee and was waiting at the door. "You know, we were on the bus, but then I said to Norman, 'Norman, let's get off the bus and go in a car. We've been here for a long time.'"

As it happened, the bus driver drove around the place three whole times. But finally, he dumped his cargo by the front door of the Bancroft. Place embassy full of marble fireplaces and early arrivals wondering if the party was going to be an intimate one of 12 people.

Nope. More like 120, who paid $85 each for the gala on the opening night of the ballet's 1980-81 season. Cocktails were first at the embassy, followed by a performance of "Othello," "Introducing" and "Double Contrasts" at Lisner Auditorium, followed by a dinner at the Federal National Mortgage Association. Mary Day, the company's artistic director, and Choo San Goh, the choreographer, were expected guests.

The whole thing was put together by the ballet's Women's Committee. "We're only two years old, and all we've done is have meetings," said Anna Maria Via, chairman of the event. "Then everybody started screaming, 'What's the matter with them?' So everybody's happy that we've had an event. Now we're going to have a meeting to review it."

Some highlights of the evening:

An hors d'oeuvres one of the waiters called "yuca" that tasted, but didn't look, like a grilled cheese sandwich. Warm, gooey and sinful.

Aldus Chapin, president of the ballet's board of directors, on the future of a rapidly growing, enterprising company that looks to be on an artistic threshhold: "The next two years are kind of a takeoff for us. We need to expand our repertory. We need to be a national instead of a regional company."

One guest recalling Galo Plaza, the former Ecuadorean president who was also ambassador to Washington in the '40s: He was a good partygoer, and he never wanted to go home. But nobody could leave until the ambassador did. Finally, somebody danced with him and said, 'Ambassador, you must go home.' So he walked around the block and came back."