i have a bag of at least 20 different RS232 cables and who knows how many adapters. I used to carry them around when answering service calls but fortunately for me, most of the devices these days are using ethernet or USB. just because cable is RS232 and mates with connectors on both devices, it is not guaranteed that this is correct RS232 cable where all lines are interconnected correctly. hence you still did not answer my question.
when debugging anything, important thing is to rule out one part of the system at a time (regardless how small step is).
1. did you verify that RS232 on that computer works? how did you confirm this?
2. did you verify that cable is correct? how did you confirm this?
etc.