If you say that everything passed to the CGI POST method is correct except for the fact that the file data remains unsent, then double check that you have a file sending capable browser (I hope you're using the same browser for these tests). Perhaps your statement is incorrect. Just like wardk suggested- double check the data with a length() before you write it to a file. Perhaps there is a discrepancy with binmode(). Unfortunately, the bare bones description taken literally (perhaps you still need to double-check some values before processing) offers no other solutions.

AgentM Systems nor Nasca Enterprises nor Bone::Easy nor Macperl is responsible for the comments made by AgentM. Remember, you can build any logical system with NOR.