I've been looking for a while but I don't find the solution to my problem. I work with rmarkdown and for some package I should use results='asis' in the chunk to generate a pretty table when I knit. However, it does never work because each time it is written attempt to use zero-length variable name. I did update et restart everything a few times.
Thank you for your answer. This code render in the Notebook. However, I only have this error message if I add result asis. But if I don't add it I can only see the graph on Rstudio but not when I knit