Standard trroubleshooting here:
1. Double check your wiring.
2. Consult your Yaesu FT-450 manual for proper wiring/pin usage
3. SOFTWARE Specific quesitons:
a. Which COM port are you using --- Software agree with your hardware connection?
b. Which RS-232 pin (DTR, RTS, CTS) are you using on that Serial port?? Again, does the software agree with your hardware connection??
We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths. -- Walt Disney