how to load R packages

I'd like to create an R visual but Power BI can't seem to locate the ggplot2 package: "R script error. Error in library(ggplot2) : there is no package called 'ggplot2'". The ggplot2 is already installed and loaded in my R environment. In addition, my R home directory is set in Power BI and I've already created basic R plots that do not require additional packages. In the R script editor, I've also tried replacing "library(ggplot2)" with "library("ggplot2", lib.loc="C:/path-to-my-r-packages")" but no success so far. Any tips you have would be greatly appreciated!