This is related to my early question, but with some changes:
\documentclass[11pt,twoside,a4paper]{article}
\usepackage{amsmath}
\usepackage{enumerate}
\begin{document}
\begin{multline}
E(y_{i})=
\left(
x_{2i}'\beta_{2}+
\frac{\sigma}{\Psi\left(x_{1i}'\beta_{1},\tfrac{x_{2i}'\beta_{2}}{\sigma},\rho\right)}
\left[
\phi\left(\tfrac{x_{2i}'\beta_{2}}{\sigma}\right)\Phi\left(\tfrac{x_{1i}'\beta_{1}- \rho\tfrac{x_{2i}'\beta_{2}}{\sigma}}{\left(1-\rho^{2}\right)^{1/2}}\right)\right.\\
\qquad
+ \left.
\rho\phi(x_{1i}'\beta_{1})\Phi\left(\tfrac{\tfrac{x_{2i}'\beta_{2}}{\sigma}-\rho x_{1i}'\beta_{1}}{\left(1-\rho^{2}\right)^{1/2}}\right)
\right]
\right)
\times\Psi\left(x_{1i}'\beta_{1},\tfrac{x_{2i}'\beta_{2}}{\sigma},\rho
\right)
\end{multline}
\end{document}
I have no idea why this is generating an error. !Missing right \.inserted
\right.
just before\\
and a\left.
just after it, but in this case they don't work well because of the\\
itself