Problem some redirect

Not always do the redirect, for example, does not go for this:
www.tregima.it/generosita/beneficenza/20...comunita-intera.html
the redirect I have done in this way
Source URL:generosita/beneficenza/2008-un-altro-pozzo-in-africa-per-la-felicita-di-una-comunita-intera.html
Target URL:beneficenza/2008-un-altro-pozzo-in-africa-per-la-felicita-di-una-comunita-intera.html
But I get 404 page
What's wrong?
Thank you

Stefano

Your target URL must be valid. Obviously it's not: www.tregima.it/beneficenza/2008-un-altro...comunita-intera.html

Your target URL must be valid. Obviously it's not: www.tregima.it/beneficenza/2008-un-altro...comunita-intera.html

Sorry but I did not understand. where I wrong?

Well that URL that you are redirecting to is invalid. Make sure you redirect to a existing URL.

Sorry but I still do not understand ... my original url is this:
www.tregima.it/generosita/beneficenza/20...comunita-intera.html
and I want to do the redirect to this url:
www.tregima.it/beneficenza/2008-un-altro...comunita-intera.html

What should I do?
Thank you

You can't redirect to a URL which doesn't exist. I don't know how to explain better.
You can redirect to a URL that returns 200 OK, not to 404.

You are probably confused and want to use alias instead. Please read the documentation (help files) for both alias and redirect and hopefully you will understand how it's used better.