Hi Liam,
If you have any DeckLink HD series card, and you configure it to receive one format (eg 1080/23.98) but the deck is outputting a different format (eg 1080/29.97) then you will see the No Video Input message. This is a little confusing because there really is video input but it is not in the expected format and so the card reports no video.
Please check that the format of the tape, and the settings on the deck, match the easy setup you have chosen in FCP. If you still cannot see video in L&C, quit from FCP and launch Deck Control. Select the appropriate easy setup from its preferences and then see if video appears in its capture window, ie the right-hand window.
Regards,
Luke Maslen
Blackmagic Design