Toc disappears after adding the acronym key

I’m trying to write my own notes.
I had added the listing of acronyms on top of my file, but when I compile my project, for an unknown reason an error pops out of my IDE, and it says:
Missing endcsname inserted. <to be read again>
The line in which it occurs is:
newacro{$varepsilon $-NFA}[AC@hyperlink{$varepsilon $-NFA}{$varepsilon $-NFA}]{Epsilon NFA}
And the tex code is this:

document.tex [that is an input for my main file]

newpage
vspace*{fill}
{centering Questa pagina è stata intenzionalmente lasciata in biancopar}
vspace{fill}
newpage
tableofcontents
newpage
input{tex/Legenda}
input{tex/Lezione1}

Legenda.tex

Legenda:
begin{acronym}[VBLAST]  % longest acronym to fix width
    acro{f(tran)}{Funzione di Transizione}acused{f(tran)}
    acro{DFA}{Automa a Stati Finiti Deterministico}acused{DFA}
    acro{NFA}{Automa a Stati Finiti Non Deterministico}
    acro{$eps$-NFA}{Epsilon NFA}
end{acronym}
newpage

Basically in my index page at the beginning, the toc seems to disappear, even if the pdf file is "correctly" generated.
I also tried to include Legenda in the toc, but the result is the same.
Thanks in advance

acro{eps-NFA}[$varepsilon$-NFA]{Epsilon NFA}