seekViewport error

Why does the seekViewport at the bottom give an error?

xyplot(Sepal.Length ~ Sepal.Width, iris, group = Species, col = 11:13,

+   auto.key = TRUE)

grid.ls(view = TRUE)

ROOT
  GRID.rect.89
  plot1.toplevel.vp
    plot1.xlab.vp
      plot1.xlab
      1
    plot1.ylab.vp
      plot1.ylab
      1
    plot1.strip.1.1.off.vp
      GRID.segments.90
      1
    plot1.strip.left.1.1.off.vp
      GRID.segments.91
      GRID.text.92
      1
    plot1.panel.1.1.off.vp
      GRID.segments.93
      GRID.text.94
      GRID.segments.95
      1
    plot1.panel.1.1.vp
      GRID.points.96
      GRID.points.97
      GRID.points.98
      1
    plot1.panel.1.1.off.vp
      GRID.rect.99
      1
    plot1.legend.top.vp
      GRID.frame.70
        GRID.VP.18
          GRID.cellGrob.72
            GRID.rect.71
          1
        GRID.VP.19
          GRID.cellGrob.74
            GRID.text.73
          1
        GRID.VP.20
          GRID.cellGrob.76
            GRID.text.75
          1
        GRID.VP.21
          GRID.cellGrob.78
            GRID.text.77
          1
        GRID.VP.22
          GRID.cellGrob.80
            GRID.points.79
          1
        GRID.VP.23
          GRID.cellGrob.82
            GRID.points.81
          1
        GRID.VP.24
          GRID.cellGrob.84
            GRID.points.83
          1
      1
    plot1.
      1
    1

seekViewport("GRID.VP.24")

Error in downViewport.vpPath(vpPathDirect(name), strict, recording =
recording) :
  Viewport 'GRID.VP.24' was not found

R.version.string # Vista

[1] "R version 2.6.1 Patched (2007-12-06 r43610)"

packageDescription("grid")$Version

[1] "2.6.1"

packageDescription("lattice")$Version

[1] "0.17-2"