In this context, each GPS model has to be supported explicitly by the flight planning software.
To some extent it depends on what "talking to each other" means. I vaguely recall that Navbox would partially work with a G496. I am pretty sure they fixed it eventually. They said they had problems with USB connections, and all the previously supported GPS models were RS232-connected.
Navbox is not really an actively developed program and has not been for some years.
Have you contacted Navbox regarding your GPS model?