knitr - error: R code interpreted as math formula in LyX -

i type code in lyx:

<<>>= data$y <- data$x @ 

this code makes error, because "$$" makes content inside them interpreted math formula. there anyway contour problem?

put code in tex box. this, highlight of text , go insert > tex code (default shortcut ctrl + l).

if happen using lyx 2.1 beta, go > specific manuals > knitr see example.

don't forget must have module loaded. this, go document > settings > modules