commas are used to separate $identifier arguments, so the script parser thinks you're passing 3 arguments to $date: "mmm", "d" and "yy", rather than just one: "mmm,d,yy", to fix this set the format to a variable first:

Code:
var %dateformat = mmm,d,yy, %timeformat = h,n,s,TT
echo -a $date(%dateformat) $time(%timeformat)