I am guessing your video recorder does not have its own digital tuner and you have connected all the equipment correctly.
Firsty you need to find out which connection your video uses to connect to freeview. It will be AV1, AV2, EXT1 or EXT2 (or similar).
To do this switch all your equipment on - set the freeview box to a channel that can't be received by terrestial tv, for quick identification,
Now toggle your video recorders AV button (or your equivalent) until you see the freeview channel.
You should now know what to record.
You will need to programme the video to record the AV or EXT instead of the channel, and make sure the freeview box is switched on to the channel you want to record for the whole time of the recording.