In her American debut in the dual role of Odette-Odile in "swan Laek" at the Kennedy Center last night, the Royal Ballet's Pippa Wylde seemed about halfway toward a full realization of the part. As Odette, the Swan Queen of Act II, she projected a sweet frailty, cowering before von Rothbart the evil magician, retreating shyly from Prince Siegfried, phrasing her steps inthe softest of contours. What was missing was the tension of inner conflict -- the gentleness threatened to become complaisance, and the sweetness bordered on the cloying.

As Odette's nefarious look-alike, Odile, in Act III, Wylde drew bravos for her surprisingly assured dispatch of the famous 32 fouettes -- surprising becasue technique was hardly the strong point in the rest of her "Black Swan" dancing, which was oftenrushed, slurred or weakly articulated. Nor did she quite manage the steely glamor that is Odile's dramatic signature. As Odette once again in the concluding lakeside act, her fine lyrical quality returned to the fore. All told, it was a respectable performance, but a somewhat dim and imcomplete one.

Much the same can be said of Derek Dean's Siegfried. With his patrician blond head and tall, slimly proportioned figure, Deane looks the part, and his dancing was exceptionally strong and stylish, from the pensive Act I solo to the fireworks of the "Black Swan" duet. When he had someone to react to -- his imperious Queen Mother, his tutor, Odette or von Rothbart -- his acting was reasonably confident. But left to his own devices he seemed dramatically at sea, so that the role had periodic dead spots and no continuous charge. Still, the makings of an impressive Siegfried would appear to be all within his grasp.

Among the incidental pleasures of last night's performance one might cite the melodiousness of willowy Bryony Brind in the Act I pas de trois; Fiona Chadwick's wan poetry as a solo swan in Act II; and Genesia Rosato's fire and Guy Niblett's snap in the Spanish Dance and Czardas of Act IIi. The vorps de ballet was once again splend, especailly in the "white" acts -- oddly, even though one could spot all manner of blemishes in the work of individual dancers, the ensemble as a whole looked seamless, fluid and eloquent.