在按照课本操作时，读取深交所云南白药代码时出现了下面这样的错误getSymbols("000300.sz")
Error in download.file(paste(yahoo.URL, "s=", Symbols.name, "&a=", from.m,  :
  cannot open URL 'http://ichart.finance.yahoo.com/table.csv?s=000300.sz&a=0&b=01&c=2007&d=7&e=14&f=2016&g=d&q=q&y=0&z=000300.sz&x=.csv'
In addition: Warning message:
In download.file(paste(yahoo.URL, "s=", Symbols.name, "&a=", from.m,  :
  cannot open URL 'http://ichart.finance.yahoo.com/table.csv?s=000300.sz&a=0&b=01&c=2007&d=7&e=14&f=2016&g=d&q=q&y=0&z=000300.sz&x=.csv': HTTP status was '404 Not Found'

希望有位大神出现可以解答
PS怎么用这个函数读取沪深300指数的数据呢？新手写论文求解答[em43]