IPFW OUCH! cannot remove rule, count 1

[nev at hotbox.ru (Andrew B)]

Hello.

I have FreeBSD 4.7-RELEASE and I use ipfw
to limit connections to my web server.

The rules are:

allow tcp from any to me 80 limit src-addr 50 in recv em0
allow tcp from me 80 to any out xmit em0

But it seems that dynamic rules are not removing cleanly so 
i can see thess messages:

Jun  5 05:53:29 www /kernel: OUCH! cannot remove rule, count 1
Jun  5 05:53:29 www /kernel: OUCH! cannot remove rule, count 2


I found this in ip_fw.c:

if (pass == 1) /* should not happen */
                        printf("OUCH! cannot remove rule, count %d\n",

So this never should happen.

Could anyone help me with my problem?

Best Regards.