[BioC] rtracklayer - export.wig issue

[Lavinia Gordon]

Dear Bioconductors,

I am trying to export a RangedData object as a WIG track, but I am 
getting this error:
 > wig <- export.wig(B18mtrack, mycon, dataFormat = "auto")
Error in export.ucsc(object, con, subformat, append, ...) :
   Track not compatible with WIG/bedGraph: Overlapping features must be 
on separate strands and every feature width must be positive
 > B18mtrack
RangedData with 33608 rows and 2 value columns across 1 space
             space               ranges   |         chr         score
<character> <IRanges>   | <character> <numeric>
1               1     [ 15865,  15866]   |        chr1   0.003188034
2               1     [ 18827,  18828]   |        chr1   0.013269155
3               1     [ 29407,  29408]   |        chr1   0.006626525
4               1     [ 29425,  29426]   |        chr1   0.004264605
5               1     [ 29435,  29436]   |        chr1  -0.004953431
6               1     [ 69591,  69592]   |        chr1   0.013326089
7               1     [135252, 135253]   |        chr1   0.035002515
8               1     [533950, 533951]   |        chr1   0.002628425
9               1     [534242, 534243]   |        chr1   0.020180509
...           ...                  ... ...         ...           ...
33600           1 [46361270, 46361271]   |       chr10  0.0051111176
33601           1 [46616291, 46616292]   |       chr10 -0.0518829821
33602           1 [46762634, 46762635]   |       chr10  0.0082029002
33603           1 [46762703, 46762704]   |       chr10  0.0017677983
33604           1 [46763197, 46763198]   |       chr10 -0.0079985873
33605           1 [46763211, 46763212]   |       chr10 -0.0001168199
33606           1 [46776799, 46776800]   |       chr10  0.0929834798
33607           1 [46915981, 46915982]   |       chr10 -0.0077882567
33608           1 [46951477, 46951478]   |       chr10 -0.0025202364

However, if I take away the last line of this object, it works:
 > B18mtrack
RangedData with 33607 rows and 2 value columns across 1 space
             space               ranges   |         chr         score
<character> <IRanges>   | <character> <numeric>
1               1     [ 15865,  15866]   |        chr1   0.003188034
2               1     [ 18827,  18828]   |        chr1   0.013269155
3               1     [ 29407,  29408]   |        chr1   0.006626525
4               1     [ 29425,  29426]   |        chr1   0.004264605
5               1     [ 29435,  29436]   |        chr1  -0.004953431
6               1     [ 69591,  69592]   |        chr1   0.013326089
7               1     [135252, 135253]   |        chr1   0.035002515
8               1     [533950, 533951]   |        chr1   0.002628425
9               1     [534242, 534243]   |        chr1   0.020180509
...           ...                  ... ...         ...           ...
33599           1 [46344329, 46344330]   |       chr10 -0.0091757753
33600           1 [46361270, 46361271]   |       chr10  0.0051111176
33601           1 [46616291, 46616292]   |       chr10 -0.0518829821
33602           1 [46762634, 46762635]   |       chr10  0.0082029002
33603           1 [46762703, 46762704]   |       chr10  0.0017677983
33604           1 [46763197, 46763198]   |       chr10 -0.0079985873
33605           1 [46763211, 46763212]   |       chr10 -0.0001168199
33606           1 [46776799, 46776800]   |       chr10  0.0929834798
33607           1 [46915981, 46915982]   |       chr10 -0.0077882567

(The .wig file loads perfectly into the UCSC genome browser)

Can anyone tell me what is wrong?
I thought it might be related to this post:
https://stat.ethz.ch/pipermail/bioconductor/2009-July/028470.html
but I can't see anything like this in my data.

With thanks for your time,

Lavinia Gordon.

R version 2.12.0 (2010-10-15)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
  [5] LC_MONETARY=C              LC_MESSAGES=en_US.UTF-8
  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] IRanges_1.8.9      rtracklayer_1.10.6 RCurl_1.5-0        bitops_1.0-4.1

loaded via a namespace (and not attached):
[1] Biobase_2.10.0      Biostrings_2.18.4   BSgenome_1.18.3
[4] GenomicRanges_1.2.3 XML_3.2-0




-- 
Senior Bioinformatics Officer
Murdoch Childrens Research Institute
Royal Children's Hospital
Flemington Road
Parkville
Victoria 3052
Australia
www.mcri.edu.au


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