For all its glittering roster of visiting ensembles, the Proms relies heavily on its house orchestras. The BBC Symphony provides the backbone of the season, playing no fewer than a dozen concerts this year, spanning a range of repertoire.

Under its new chief conductor Jiri Belohlavek, it is sounding better than ever in mainstream repertoire such as we heard on the first night last week. For its second concert, however, consisting of more recent music, the orchestra was under principal guest conductor David Robertson and all was not well.

A trio of complex and difficult scores proved too great a challenge and a new commission, from Sam Hayden, had to be truncated at the last minute. Hayden's Substratum is written for a large orchestra with a powerful bass section, underpinned by contrabass clarinet and contrabass trombone. The final three sections (there are seven in total) that are all we heard are massive constructs of sound: fluid, layered blocks - rather like those of Magnus Lindberg but without the rhythmic momentum. Until the BBCSO is able to present the entire work and we can hear those final sections evolve out of the earlier ones, it is impossible to judge its success or otherwise.

Leonard Bernstein's Symphony No2, The Age of Anxiety, is a more sombre piece than many of his better-known scores, the characteristic jazziness confined to the final sections. Yet it can and should be more engaging than it seemed here.

Likewise Charles Ives's Fourth Symphony, a revolutionary collage of hymn tunes and other scraps of melody that nevertheless has a serious purpose: tackling the meaning of life itself. An Ives symphony should be one of the great Proms events, but this performance provided a lacklustre conclusion to a disappointing evening.

• Information: www.bbc.co. uk/proms, 020 7589 8212.