NGINX empty session

http://serverfault.com/questions/495551/nginx-empty-session

Video with the error http://youtu.be/FDXXKo5LPy8

I installed the new 1.2.8 Nginx server with the same configurations from 1.2.1 and now I'm getting bugs to get sessions (flash sessions).

By default, I'm get error on every page doing that. But I Googled and found this config:

fastcgi_buffer_size 512k;
fastcgi_buffers 16 512k;
Now, some pages I get what I want, but this is because the sessions isn't so big.

How can I fix that?

Video with the error http://youtu.be/FDXXKo5LPy8

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Already tried this directives:
client_header_buffer_size 512k;
large_client_header_buffers 16 512k;
client_body_buffer_size 1m;
client_max_body_size 2m;

No php errors, no nginx errors. This bugs I get on nginx 1.2.8 (windows and linux/debian on amazon ec2).
I tested this on local debian with nginx 1.2.1 and all worked fine.