Running squid behind a dial-on-demand-link

Hi!

I have an autodial-dynamic-ip connection to the internet by isdn4linux.
My Provider has blocked Port 80 and is running squid an this Port. So
I'm forced to do all http stuff through his proxy.
I configured my locat proxy to do all querys through my providers proxy
by steeing this proxy as the only parent.

But sometimes I get this:
---
ERROR

The requested URL could not be retrieved

While trying to retrieve the URL:
http://www.cineca.it/proxy/search/html/9706/0508.html

The following error was encountered:

    Unable to Retrieve

The system returned:

    No neighbors or parents were queried and the host is beyond your
firewall.

The cache administrator may need to double-check the cache
configuration.

This means that:

    The requested URL can not currently be retrieved.

Generated by squid/1.1.10@bonk

---
The Log shows:
97/07/13 01:44:41| protoCantFetchObject: FD 12 No neighbors or parents
were quer
ied and the host is beyond your firewall.
97/07/13 01:44:41| -->
'http://www.cineca.it/proxy/search/html/9706/0508.html'
97/07/13 01:44:41| ERR_CANNOT_FETCH:
http://www.cineca.it/proxy/search/html/9706
/0508.html
---
I get this when the link is down (squid should trigger auto-dial) AND
when the link is up (so there should not be any access problems for
squid at all)
Here a bit of my squid.conf:
# bonk (192.168.111.1) is the name of my local squid in my LAN
# proxy.ndh.com is the name of my providers proxy.
http_access allow  all
icp_access  allow  all
miss_access allow  all
passthrough_proxy proxy.ndh.com:80
cache_host proxy.ndh.com parent 80 3130
cache_host_domain proxy.ndh.com
inside_firewall bonk
local_ip 192.168.111.1
Has anybody an Idea where the Problem could be?
Please be so cind to cc my E-Mail adress, because I only read this
Mailinglist by the Web-Interface.
Thanks
Max Dornseif