New Color Box Type code error

[lloyd]

This code throws an error: 
 
New Color Box Type Name cBoxA 1 col back=gray!25!white,colbacktitle=black, 
colframe=black!;75!black, fonttitle=\bfseries, title=\listno\,##, 
width=\textwidth

\begin{cBoxA}
{}
 Evidently related to the parameter after cBoxA. My notes say that there should 
be the term Arguments after cBoxA, but when I try that I still get an error.
 
Can some kind guru show me the way?
 
Best wishes,
 
LRP