Hi,
It seems that you're developing the VI in the Windows 98 machine, building the executable and then running the Windows 95 computer. Are you using NI-VISA?, If so, you also need to install the VISA runtime engine (you can download it from www.ni.com).
Are you getting any error message or is it simply not sending any data?. How's the application behaving?
Run a loopback test on the target computer, using hyper terminal. That way you can determine if the serial port is working properly.
Let me know if you have questions.
DiegoF
National Instruments