包XBRL无法下载架构

XBRL包无法找到具有以下内容的现有XSD：

url <- "https://www.sec.gov/Archives/edgar/data/51143/000104746916010329/ibm-20151231.xml"
xbrl.vars <- xbrlDoAll(url, cache.dir = "XBRLcache", prefix.out = NULL, verbose = TRUE)

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然而，XSD是存在的。我正在OS X El Capitan上运行R 3.3.2。

您是否尝试过通过下载xsd并将其与所需的任何文件放在一个目录中来消除访问问题？注意：它所依赖的xsd/XMLURI引用中有多个导入。

Error in fileFromCache(file) : 
  Error in download.file(file, cached.file, method = "auto", quiet = !verbose) : 
  cannot download all files

In addition: Warning message:
In download.file(file, cached.file, method = "auto", quiet = !verbose) :
  URL 'https://www.sec.gov/Archives/edgar/data/51143/000104746916010329/ibm-20151231.xsd': status was '404 Not Found'