"LaTeX Error: Too many math alphabets used in version czt"

This error means you have used more than 16 math symbol fonts (latex limitation).

Solution 1:  (http://valis.cs.uiuc.edu/blog/?cat=37)
Bypass this limit by specifying the only used font, e.g.

$\text{\usefont{U}{bbm}{m}{n}{H}}$ 

 Solution 2: (Work for this case)
 Replace the txfonts package with mathtools
Or remove the txfonts package if you don't need it

%\usepackage{txfonts} %\varparallel
 \usepackage{mathtools}

Solution 3:
too many math alphabets in version normal

\usepackage{amssymb}

\newcommand\hmmax{0} % default 3
 % \newcommand\bmmax{0} % default 4
 \usepackage{bm}