With the early version you are using if you are connected to the internet and have sharing set and you click on an aircraft it will download the data from the server. assuming it is in the database.
You could go to MyLog/Grids/Tools Populate/ and it will populate the ones you have picked up within the timescale you set, you may need to do it 3 or 4 times to get them done though.
If you download and install V5 you would have the ability to download and new database each day. At this time we have around 239,000 records in the aircraft table compared to the 80,000 or so you will probably have, hence the reason for your blanks registrations.
Alan