# circuitikz units not reconized

So, I'm having an issue with LaTeX recognizing and rendering the units with how I understand units should be done with circuitikz

Here is my code:

\documentclass{standalone}
\usepackage{tikz}
\usepackage{circuitikz}
\usepackage{siunitx}

\begin{document}
\begin{circuitikz}
\draw (0,0) to [R=$\SI{100}{\ohm}$] (2,0);
\draw (3,0) to [R=5<\ohm>] (3,2);
\draw (0,-2) to[R,label=\mbox{$R_1=\SI{2}{\ohm}$}] (2,-2);
\end{circuitikz}
\end{document}


I have looked at this post. Which seeks to answer this question, but the code provided there is not working. I've gathered the other ways to do this from other posts, but they do not render either.

This is what my code gives me:

You have to use \usepackage[siunitx]{circuitikz}.
• Doing this does not resolve the problem (I had tried that too). The difference in the output with that rather than \usepackage{circuitikz} and \usepackage{siunitx} is that the "!?" disappears. The units desired do not render with this. – Jeremie Mar 14 '16 at 18:28