Hi
I had the same problem as luiz_monza. I came across this page while looking for a solution to the problem.
After several attempts, I found the solution (I would like to share it with everyone who also has this problem):
Solution: In the "Navigraph FMS Data Manager" you have to enter manually the main directory from the IXEG B737 (.... / X-Aviation / IXEG 737 Classic).
If you let Navigraph create "automatically" the path for the IXEG B737 himself, he creates a ("second") sub-directory fmc_data (.... / X-Aviation / IXEG 737 Classic / fmc_data / fmc_data) in the fmc_data subdirectory and then it does not work.
Regards
dhondt