Won't let mesave to SD card

[musician1928]

I've been trying to convert this model in Replicator G to print on the MBot.  I have all of the settings correct.  I generate the G code (it takes about 42 minutes) but will not give me the option of saving it as a .x3g file so that I can print it.  I have done the other half of this model, twice, on the MBot using the exact same settings but with this one, no luck.  Anyone have any idea what I can do to fix this?

Cheers,

John