Seam not work with proxy

[alphaonex86]

Hi, seam not work with proxy:

set $store_path /tmp/pngquant;
location ~ \.png$ {
    root $store_path;
    try_files @proxy @pngquant;
}
location @pngquant {
    pngquant on;
    pngquant_buffer_size 1M;
    pngquant_colors 256;
    pngquant_dither on;
    pngquant_speed 1;
    pngquant_store $store_path$uri;
    pngquant_store_access user:rw group:rw all:r;
}

    location ~ /.* {
        proxy_pass             http://$host;
        proxy_set_header       Host $host;
        proxy_http_version 1.1;

        proxy_cache MYAPP;
        proxy_cache_valid 200 31d;
        proxy_cache_valid 302 301 31d;
        proxy_cache_valid 404 24h;
        proxy_cache_valid 500 72h;
        proxy_cache_use_stale updating;
        proxy_cache_background_update on;
    }