Using a tv as external screen?

[myname77]

Hi I wanna use a newly bought samsung tv as external screen to my macbook pro (2012). I have yosemite. Im using mini display to hdmi adapter.
The tv turns up in the mac and i can choose to use the tv resolution in the mac but the computer screen doesn't turn up on the tv screen. The tv says
theres no cable connected and no source. Is there any preference in the mac i should change or could it be something wrong with the cables? But if there is something wrong with the cables.. why does the mac find the samsung screen then?

thanks for any help

[Baldrick]

Have you tried all hdmi-inputs on the samsung tv? Try also different resolutions.

Can you connect other hdmi devices to the tv?

[myname77]

Hi Thanks for the reply. I bought a new hdmi cable and then it worked like there never was a problem at all. Strange that the other hdmi cable worked with xbox
but not with the computer thou.