auto box

Have a converted 110 running a v8 3.5 carb with auto gearbox.

I used it yesterday and all worked fine but when i used it to day i cant get reverse!
Drive and 123 still works fine.
When you select reverse it make a noise but does not engage.
Have tryed easing rod adjustment etc but still no go!
Any ideas?
Thanks
Leigh

Ask the range rover boys.
Not too many series with a auto box