nat and 2 public ipaddresses

Hi,

I have one internal and 1 public nic.
Since today I added another secondary ipaddress to the public nic.
I created a static nat route from this secondary public ipaddress to an
internal host.
Since I added this static route I can not use the internet anymore from my
pc. I do not use a proxy!
After I enabled dynamic and static for this secondary ipaddress, it worked
again.
Is it not possible to only use dynamic nat for the primary address and use
static only for a static nat pair?

regards,
Michael