! LaTeX Error: Something's wrong--perhaps a missing item

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return>  for immediate help.
 ...

1.14      end{align}
                     %

documentclass{article}
usepackage{amsmath,amsthm}
newtheorem{theorem}{Theorem}[section]

begin{document}%

begin{theorem}%
begin{enumerate}%
    begin{align}%
    intertext{item Condition $A$}
    a &= b
    intertext{item Condition $B$}
    c &= d
    end{align}%
end{enumerate}%
end{theorem}%

end{document}%

documentclass{article}
usepackage{amsmath,amsthm}
newtheorem{theorem}{Theorem}[section]

begin{document}%

begin{enumerate}%
    begin{align}%
    intertext{item Condition $A$}
    a &= b
    intertext{item Condition $B$}
    c &= d
    end{align}%
end{enumerate}%

end{document}%