I suspect - I don't know and just guess...
Modern TVs have the ability to show Digital TV (DTV) - Analogue TV (ATV)- Input from a DVD box (AV1 say) From a Computer etc...
My TV alows me to select 8 different input sources.
The TV does not know which input I wish it to display - usually it's digital - DTV but not always - I have to tell it what I want.
There's a button on top of my set with a symbol showing a circle with an arrow going into it - look for something similar on your set - call up Digital TV.
The selector may be on your remote control - it might be marked Source.
Good luck...
Peccavi
March 2013