Was anything ever connected to the TV with either DVI or HDMI?
You might try a different HDMI cable, since the DVI to HDMI cable will not pass audio - so you'd need to get a separate audio connection if you go that route. HDMI-to-HDMI is the easiest if you can get it to work.
Also check to see that your source box is sending the signal specifically through the HDMI port to the TV. Many devices will default on composite (yellow AV) or component (Red Blue Green).
I have a samsung tv model la26r71bx/sap. it has only 1 hdmi input and it is label as dvi/hdmi input port. The tv also has a dvi audio input port, which is next to this dvi/hdmi port( i guess it can also be use by a dvi-hdmi cable/adapter to connect to these 2 port). These 2 port has not been used for 1-2 yrs since i bought this tv.
Recently, i have bought a hd set top box and a hdmi cable(hdmi male port on both ends)and intend to connect these 2 equipment together. However, my samsung tv cannot detect this hdmi input. hdmi input source was show as grey out when i try to select it from my tv.
I'm not sure if the cable spoilt (I have only 1 cable and this is new) or hdmi/dvi port spoilt or if i have bought the wrong cable(should bought dvi-hdmi cable instead).
Anyone here enounter similar issues? Please advise. 10s