Your message did not indicate the NT+ code number that you are using.
Some Raymarine products may not reconize a C-card with a .00 version.
Versions .01 and above corrected this problem.

Also some Raymarine units will only reconize an NT+ C-card in the top
slot of the unit. Raymarine introduced new software to correct this
issue. I suspect that your symptom may be related to one of these
issues, as you have confirmed that your NT+ C-card operates correctly
in another unit.

J. McQuade
C-MAP/USA