Arrow tip not showing

Question

Why are there no arrow tips between A -> B, B' and B -> C ?

\documentclass{article}
\usepackage{tikz}
\usepackage{amsmath}
\usepackage{tikz-cd}
\usetikzlibrary{matrix, calc, arrows}
\usetikzlibrary{decorations.pathmorphing}

\begin{document}
\begin{tikzpicture}[>=triangle 60]
\matrix[matrix of math nodes,column sep={20pt,between origins},row
  sep={40pt,between origins},nodes={asymmetrical rectangle}] (s)
{
  & |[name=A,draw,rectangle]| A & & & & & |[name=D,draw,rectangle]| D \\
  & & |[name=B,draw,circle,inner sep=2pt]| B   & & & |[name=C,draw,circle,inner sep=2pt]| C   & \\
  & & |[name=B1,draw,circle,inner sep=2pt]| B' & & & |[name=C1,draw,circle,inner sep=2pt]| C' & \\
};
\draw [->] 
  (A) |- (B) 
  (A) |- (B1) 
  (B) -- (C)
  (B1) edge (C1)
  (C) -| (D) 
  (C1) -| (D) 
;
\draw[->, line join=round, decorate, decoration={zigzag, segment length=10, amplitude=1.9,post=lineto, post length=4pt}]
  (A) -- (D)  
;  
\end{tikzpicture}
\end{document}

Answer 1

All credits go to Qrrbrbirlbel for this answer that I just adapted (since you're new to TikZ and it would be hard to find what to add).

\documentclass{article}
\usepackage{tikz}
\usepackage{amsmath}
\usepackage{tikz-cd}
\usetikzlibrary{matrix, calc, arrows}
\usetikzlibrary{decorations.pathmorphing}

\tikzset{
  a/.style={rectangle,draw},
  -|/.style={to path={-| (\tikztotarget) \tikztonodes}},
  |-/.style={to path={|- (\tikztotarget) \tikztonodes}},
  |-|/.style={to path={
      let \p{qrr@to@start}=(\tikztostart), \p{qrr@to@target}=(\tikztotarget) in
      -- (\x{qrr@to@start},.5*\y{qrr@to@start}+.5*\y{qrr@to@target}) -- (\x{qrr@to@target},.5*\y{qrr@to@start}+.5*\y{qrr@to@target}) \tikztonodes -- (\tikztotarget)
    }
  }
}

\begin{document}
\begin{tikzpicture}[>=triangle 60]
\matrix[matrix of math nodes,column sep={20pt,between origins},row
  sep={40pt,between origins},nodes={asymmetrical rectangle}] (s)
{
  & |[name=A,draw,rectangle]| A & & & & & |[name=D,draw,rectangle]| D \\
  & & |[name=B,draw,circle,inner sep=2pt]| B   & & & |[name=C,draw,circle,inner sep=2pt]| C   & \\
  & & |[name=B1,draw,circle,inner sep=2pt]| B' & & & |[name=C1,draw,circle,inner sep=2pt]| C' & \\
};
\draw [->] 
  (A) edge[|-] (B) 
  (A) edge[|-] (B1) 
  (B) edge (C)
  (B1) edge (C1)
  (C) edge[-|] (D) 
  (C1) edge[-|] (D) 
;
\draw[->, line join=round, decorate, decoration={zigzag, segment length=10, amplitude=1.9,post=lineto, post length=4pt}]
  (A) -- (D)  
;  
\end{tikzpicture}
\end{document}