First you have to make sure that data is comming out of the USB/com port, this is where a break-out box is a must for working with RS232.
Also make sure the PC side is set to software H.S. & Hardware Handshake off.
On this set up I would tend to use a three wire cable and jumper out the H.W. Hansdhake both ends.
On 9pin jumper 1-4-6 & 7-8 on 25p 6-8-20 & 4-5
Use connection only from 9p to 25p 2 -2, 3-3, 5-7.