> library(xlsReadWrite)
> xls.getshlib()
Loading required package: tools
--- xls.getshlib running... ---
  - download.file from 'http://dl.dropbox.com/u/2602516/swissrpkg/bin/win32/shlib/xlsReadWrite_1.5.4_dll.zip' (timeout: 60)
错误于copyOrDownload(url) :
  downloading 'http://dl.dropbox.com/u/2602516/swissrpkg/bin/win32/shlib/xlsReadWrite_1.5.4_dll.zip'
to 'C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\RtmpuIZwiA/xlsReadWrite.zip' failed
此外: 警告信息：
In download.file(url, fpzip.temp, method = "internal", quiet = TRUE,  :
  无法打开: HTTP状态是'0(nil)'
>
请问出现上面的错误是什么原因啊？该怎么改正？