Didn't know this until today.

2 days ago, my daughters remote for the tv wasn't working. So I decided it was probably damaged. So I bought a new remote control that was suitable for the TV in question.

Came to use the new remote and that didn't work.

Not knowing what to think, I googled to see if I could find a way of checking the remote beam to make sure it was working on either or both of the remotes. The TV remotes didn't give a light like some do.

Basically all I needed to do was point the remote at my digi camera on my mobile phone whilst it was turned on. Then press the power button on the remote and if it is working you should see a bluish light in the viewer.

So I gave it a go.
The new remote worked
The old one didn't.

I was about to get in touch with the supplier and check that I had been sent the correct remote, but decided to disconnect all cables from the TV and reconnect. Having done that, I then tried the new remote and hey presto it worked.

However that simple process of checking the beam helped me considerably.

So thought I would post here for anybody else that might get the same problem.

Here is the link that provided me with the info.
http://www.wikihow.com/Check-if-a-Remote-Control-is-Transmitting-an-Infrared-Signal

Isn't the internet wonderful