I’m pretty sure you were using Sweave instead of knitr. If you were using RStudio (you did not say it but I guess so), you need to change the global option (or project option) to knitr:
I’m pretty sure you were using Sweave instead of knitr. If you were using RStudio (you did not say it but I guess so), you need to change the global option (or project option) to knitr: