Hi and welcome to the forum, Debi.
I am not sure I understand your folder & file structure, but do you have it like this:
cgi-bin which have a folder named dada and in that another folder named DADA and in cgi-bin/dada a file named mail.cgi?
Also, note that the DADA folder must be with upper-case letters.
Another thing is to see so dada_files are placed outside the public_html and if all folders and mail.cgi have the proper permission.