Local forwarding with "iptables" gives "invalid arguments"

Dear all,

while trying to set up a reverse proxy I ran into serious trouble with
iptables.

I'm trying to forward locally generated traffic to a remote machine.
But a command like

# iptables -A OUTPUT -t nat -p tcp -d 192.168.1.154 -j DNAT
--to-destination 192.168.1.250

fails with the laconic message "iptables: Invalid argument" which is
not helpful in any way.

I' running SuSE Linux Enterprise Server (last try was with their kernel
2.6.5-7.191-default)
and, YES, I have already rebuilt the kernel after setting
CONFIG_IP_NF_NAT_LOCAL=y.

Actually I built several kernel by now, the last one with all netfilter
stuff compiled in (not as modules).

However, the result stays the same whatever I try, that damn "Invalid
argument".

How can I find out what is the reason for that, how can I debug this
kind of stuff in a way that enables me to find what "argument" is
"invalid" here for what reason.

Benno