How to access /var/tmp/message.msg from cgi-script through a browser

hi,

i have a cgi-script that is suppose to decode a mime-message and write it to a temporary file.
It runs well at the prompt but when i try it through the browser it does not write to the file. I've set debug like this:

unless (open (EP,"/var/tmp/message.msg")) {
print "Cannot access file";
}

and the browser returs Cannot return file.

Can anynone please tell me how to write to a file on the hard disk from the cgi script.

Its really urgent thank you;