Though I've seen the posts before, this time they worked for me. :)

The mistake was silliest one possible. I didn't put two '\n's at the end of print "Content-type: text/html"; It costed me so many hours. I was so determined that the fault is on configuration file that I never bothered to scrutinize the scripts. By the way, I never thought omitting these characters would stop the script from being executed. CGI programming is very strict, I must say. Thank you zek152 and everybody else