As the National Chamber Orchestra's program notes tell us, "There is a sharp contrast of soloist and tutti" in Mozart's Piano Concerto No. 20 in D Minor. In addition to the contrasting themes of which the musicologists speak, audiences at Friday night's concert heard some unwelcome contrasts between the strengths of pianist and orchestra.

Local pianist Brian Ganz had endeared himself to the audience before he played the first notes. While negotiating the cramped path to the piano, he tripped and almost hurtled a microphone into the Duke Ellington Theater's front section. He came up grinning. That nerve and confidence translated into a reading that was fluid and almost conversational, but moody and tempestuous when necessary.

The orchestra, on the other hand, suffered from technical foul-ups. Cracked notes and flubbed entrances in the brass section were devastating.

Underlying these difficulties was the more nebulous problem of focus. Conductor Piotr Gajewski is certainly an exuberant presence on the podium, but little of his energy found its way into the music. Much of this concerto's power -- its dramatic insinuations and its romantic moods -- remained unharnessed. Even those famous first pulsating strains of the introduction were rendered rather indifferently. This is not what one expects to hear from an orchestra that calls itself "National."

The string section, however, was never short of professional excellence, in the Mozart as well as elsewhere in the program -- especially the deft passage work in the outer movements of the Mendelssohn "Italian" Symphony, and the soft, mellow tinting in the Sibelius "Valse Triste."