我打开R软件，然后 程序包→install package from local files→把pcalg程序包放进去，然后显示成功，但是在library（pcalg）的时候出错。显示如下：
> install.packages("C:/Users/Lenovo/Desktop/pcalg_2.6-8.zip", repos = NULL, type = "win.binary")
Installing package into ‘C:/Users/Lenovo/Documents/R/win-library/3.5’(as ‘lib’ is unspecified)
package ‘pcalg’ successfully unpacked and MD5 sums checked
> library("pcalg")
Error in library("pcalg") : 不存在叫‘pcalg’这个名字的程辑包



这是为什么