安装tseries包总是不成功，是什么原因呢？经常遇到一个包安装不了的情况，这是什么原因导致的呢？
Warning in install.packages :
  downloaded length 4096 != reported length 321126
Warning in install.packages :
  error 1 in extracting from zip file
Warning in install.packages :
  cannot open compressed file 'tseries/DESCRIPTION', probable reason 'No such file or directory'
Error in install.packages : cannot open the connection