in reply to
perltk: error getting values from dynamically generated combo boxes
Tk::Error: bad listbox index "": must be active, anchor, end, @x,y, or a number at /usr/intel/pkgs/perl/5.8.5/lib/site_perl/5.8.5/x86_64-linux/Tk.pm line 247
So. You're giving a listbox index that is either an empty string or perhaps undef. The solution is to not do that :)
Try printing out the values you're using, and then see where the bad value is coming from.
You could also make a temporary tweak to Tk.pm, and have it confess instead.