Just the map on the SD should do fine.
Did you put in in the root or in a separate folder?
Couple of suggestion to try
Can you use the map at all ?
Can you tell TT to switch to the map on the sd card?
If so, is there a 'mapsettings.cfg' on the card?
If yes, backup the file, then delete it on the sd and see if it recreates the file. (input a dummy favorite)
If you cannot delete it, it might be marked as 'read only' --> then remove the read only flag
A remark on the side.(once the map is solved)
I noticed you are using nc 8.351, which it pretty old.
Why not update it to a newer version so you can enjoy the full features maps like 880.3810.
Your 930 should not have any problems with that.
IO removed the North_AMERICA_2GB map from the device and installed teh 880.3868 map on the internal memory which workd fine.
Now I moved the mp from the internal memory to teh sd card but not working.
When trying to add new favorite getting the error message "unable to store map file access error"