PF and "set limit src-nodes" error.

[Andre]

I can't set 'limit src-nodes' with pfctl on a FreeBSD 5.4-RELEASE 
system. This is the error I get:

# echo "set limit src-nodes 1000" | pfctl -f -
pfctl: DIOCSETLIMIT: Invalid argument

I'm able to set 'states' and 'frags' just fine:

# echo "set limit { states 50000, frags 2000 }" | pfctl -f -

Since 'limit src-nodes' is documented in the pf.conf(5) man page, my 
guess is I'm missing something in the kernel configuration. I'm running 
GENERIC with the following additions:

device          pf
device          pflog
device          pfsync

Anything else I should have put in there?