reversing light failure

[skullhead]

Hi all, I need some help if possible.

Car passed mot last month, but, yesterday I found out my reversing lights were not working.

I have just followed the how to in tech section, and after cleaning I tried the button manually and they worked fine, so I thought great, job done.

Put wheel back on and started engine with my wife behind saying that my lights were still not working when gears were put in reverse.

Now I need help as to what else could be wrong.

Thanks in advance to all

paul