The Harvard-Radcliffe Callbacks gave a polished and versatile performance in front of a large Sanders Theater crowd at their Pajama Jam Saturday night. With varied musical styles and funny transitions between songs, the group skillfully showcased their talents, but a few flaws in the jam kept it from being the out-and-out success it could have been.

From the start, when the Callbacks "awoke" in their pajamas with a string of bad breath jokes, the audience was in an a capella frenzy, ready for good singing and good fun. Well, the crowd got occasional fun and intermittently good singing. The tunes, which ranged from Michael Jackson to Talking Heads, were generally well-executed and energetically performed. Sometimes, though, the pace of the performers flagged during songs.

The opening number, Paul Simon's "Diamonds on the Soles of Her Shoes, was sung too low for Nara Garber's lead, making the much anticipated start anticlimactic. And the Callbacks's rendition of the Supremes' "You Can't Hurry Love," despite humorous staging, died in the middle of the song and then dragged on uncomfortably. Other songs, such as "Human Nature," featured strong lead vocals but soon grew tire-some. This was more a reflection of the songs themselves than the way they were performed.

Despite these problems, the jain had several colorful moments. Certain voices, such as Jessica Walling's in "I'm Going Bananas" really shined, and the skits between songs were cleverly conceived and performed, if not really true to the theme. The hilarious parody of the TV dating show "Love Connection," although not terribly subtle, drew cheers from the audience.

The audience may have experienced a healthy does of a capella pleasure, but it did not achieve a capella peace of mind. Although the Callbacks sampled a wide variety of musical styles, their jam lacked consistency. In general, the group established a greater rapport with their audience on those numbers which included humor, such as the Texas-flavored "Good Enough for Now."

Onyx, a rhythm and blues a capella group composed of Harvard students, opened for the Callbacks. Performing three original songs, a popular cover and an encore of "Down by the River-side," Onyx wowed the audience with exciting vocals and a relaxed sense of humor. The Middlebury Dissipated 8, a nine-man group which also performed before the Callbacks, sang their tunes with polish and wry humor, except for a dreadful version of Smoky Robinson's "Tracks of my Tears."