Varnishd 1.1.2 returns 5xx

[Lin Jui-Nan Eric]

Dear All,

I am trying to replace squid with varnishd for reverse proxy. But I
found varnishd 1.1.2 sometimes responses 5xx, while varnishd 1.2 works
correctly.

I tested with the command below:
    cat a_long_url_list | wget -i - -B http://rproxy{1,2}/ -O
/dev/null -o /dev/stdout | egrep -i '(response|fail)' | grep -v 200

where rproxy1 running varnishd-1.2, and rproxy2 running varnishd-1.1.2
The output of wget which connected rproxy2 is:
HTTP request sent, awaiting response... 503 Service Unavailable
HTTP request sent, awaiting response... 503 Service Unavailable
HTTP request sent, awaiting response... 503 Service Unavailable
HTTP request sent, awaiting response... 503 Service Unavailable
HTTP request sent, awaiting response... 503 Service Unavailable

All OS is FreeBSD 7.0. Thank you for any suggestions!