installing data.table results in “there is no package”

I am new to R and have to install a data.table into my workfile. Right now, I have implemented:

install.packages("data.table")
require(data.table)

However, when I run this part (Ctrl + Enter) I get the following error in the console-window:

Loading required package: data.table

Warning message:

In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE, : there is no package called data.table

Is this truly an error or can I work on it further without problems? Thank you in advance!!