Writing equations with fractions and greek letters

Writing equations with fractions and greek letters

I'm trying to write this equation below and using the \usepackage{amsmath}, but I'm getting the error ! Argument of \frac has an extra } so I still don't know what I did wrong. And how can I make everything upright and not italic?
\begin{eqnarray}
\dot{\varepsilon} = A{\prime}{\prime}{\prime}\dot\frac{\sigma\dot\omega}{k\dotT}\dot\frac{1}{d^2}\left(1+\frac{\pi\dot\delta}{d}\dot\frac{D_{KG}}{D_v} \right)
\end{eqnarray}