Assigning static ip to MBL

Hi I want to assign a static ip to MBL. Seems the MBL will get a new IP when DHCP is used. It (or the camera causes a problem) seem cause problem when a wireless camer get connectged, so I want to assign a static ip. BTW:The camera had a static IP and the MBL  was assigned same ip.

So in the option for MBL

IP address: I know what to set this

Netmask: 255.255.255.0  ->is this correct?

Gateway: Does this need to be set and if so to what, the default gateway IP from m router?

DNS server: same as primary dns server as router?

Why does the MBL need gateway/DNS servers fields for, accessing remotely

Gave a try, set subnet mask to 255.255.255.0,

set gate to router gate address and

DNS server to DNS server IP.

Clicked save->continue, 

MBL replied with 

31239  - The gateway is not in the same subnet as the IP Address.

So what should subnet mask be set to?

Just do dhcp, and then note what the MBL uses.  Then go back to static and use the same things.

Those fields are blank with dhcp:

net mask

gateway

I know what to set DNS  server to.

Then use the same values your PC itself uses.