That's very vague amount of information.
How far are you in miles?
Can you receive anyone? (As a test you might want to listen in on CH16 and make sure you are covering a time when a CG all station broadcast should happen:
https://www.gov.uk/government/public...mation-leaflet (page 4-6 of the leaflet)
NB times are published in UTC (British Winter Time)
Most common reason to hear nothing is squelch is set too high.
If you can hear other traffic, but not raise NCI - 2 steps. Can you check with another station if they can hear you (Marina, Boat, CH16 CG if absolutely necessary).
If they are able to receive and you can hear them, then there is likely to be some issue with talking to NCI. Either they are unmanned for some reason, or you are out of range // tech issues. I'd probably give them a phone and see what they said. They may say they can hear you but you can't hear them back etc. 01726 817068
Presumably you did call them on 65? They listen on 16, 10, 65, 67 but would normally only respond on 65.