proxy and 301 codes

[Paul B]

I am using nginx as front-end with apache as backend for (for mod_php)

If I have a 301 redirect on a page that is proxied to apached,
 i do not get
redirected but rather see a page that says

Moved Permanently

The document has moved here.

with (here) being a link to the new location. 
If i go to the page on my backend
port, i get redirected automatically.
 How can i get the backend to tell nginx to  
redirect??