I assume you are using DVB-T.
Many factors can affect Digital Terrestrial; Quality of aerial and downlead, transmitter power, local conditions, etc.
In digital transmissions instead of each channel being broadcast on a separate frequency, several channels are mooshed together in a Multiplex (mux) which is transmitted at a single frequency.
In your case we can see that the 4 channels you can't receive are on the same Mux.
You might be not able to pick up this mux for several reasons:
1) It is being transmitted at a power that you cannot pick it up. This might be due as in the UK that the power is lower to stop interfering with neighbouring Analogue channels. So you may have to wait for analogue switch off to pick it up.
Ensure that your aerial/downlead are good quality and pointing towards the correct transmitter. (You are using the correct transmitter for your site, are you? Just because it's the nearest, doesn't always mean you use that transmitter. Sometimes local geographic features mean you have to point to one further away.) and/or use some kind of amplifier.
2) The actual transmitter is lower down the transmitter tower, so you don't have visibility of the signals.
3) Some problem with local interference or problems with your aerial/downlead that causes problems with transmissions at that frequency. Well, as above check your aerial/downlead for breaks, water ingress, damage and connector problems. The Belling-Lee push on connectors aren't very good, the RG-56 screw on type are generally much better. Also check that devices switching on such as a freezer, fridge or boiler are not generating the interference.
Hope this helps
Bruce S.