在R中，在我安装了sem软件包之后，库（sem）中出现了错误，没有名为＆＃39; sem＆＃39;

Question

> utils:::menuInstallPkgs()
--- Please select a CRAN mirror for use in this session ---
Warning in install.packages(NULL, .libPaths()[1L], dependencies = NA, type = type) :
  'lib = "C:/Program Files/R/R-3.1.0/library"' is not writable
trying URL 'http://cran.cnr.Berkeley.edu/bin/windows/contrib/3.1/sem_3.1-4.zip'
Content type 'application/zip' length 938488 bytes (916 Kb)
opened URL
downloaded 916 Kb

package ‘sem’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in
        C:\Users\me\AppData\Local\Temp\RtmpqEbj6i\downloaded_packages
> library(sem)
Error in library(sem) : there is no package called ‘sem’
> 

我安装了名为＆＃39; sem＆＃39;的软件包，我可以看到“＆＃39; package＆＃39; sem＆＃39;成功解压缩并检查MD5总和＆＃39;但是当我检查加载页面或使用库代码时，R表示没有名为“sem”的软件包。 即使是我的教授也不知道，当他在电脑里尝试这个时，它运作良好。但不是我的台式机和笔记本电脑。请帮帮我。