what is wrong with this rdr rule?

["Ted Goodridge, Jr" <tedgoodridgejr@acm.org>]

I'm trying to redirect all packets coming out from my network 192.168.0. on
ports 2500-4000 to be redirected to the external ip on those same ports.

This is my rule:

rdr on $Int proto tcp from any to any port 2500:4000 -> $ExtIp port 2500:*

pf tells me there is a syntax error.

$Int = the internal interface
$Ext = the external IP

Where is the error?
Ted