Can't access my modem configuration page?

Hi guys, for the past day I have been trying to configure some settings on my modem and to do so I must access it from it's ip (192.168.250.1). However, when I load that ip in my browser it does not connect. How can I fix this?

By the way, I am currently connected through my D-Link 254 router which is connected to my WiMax modem.

2012-01-29T16:41:37Z

@Michael My router has a private ip of 192.168.0.1 because of a Double NAT issue which I am trying to fix by going to the modem's configuration page. I am pretty sure that it is 192.168.250.1 because that is what my router ISP Gateway says, along with ipconfig in cmd when I directly connected to the router from my computer.

?2012-01-29T16:35:53Z

are you sure your modems ip is that. Normally it's something like 192.168.1.1 or 192.168.0.1 You also need to be connected to the router either through a wired connection or a wireless one to do it you can't simply type the ip in. (you might have already be on the internet as you are asking this question but in case you were trying to do it from a unconnected laptop or something or simply used a friends or relatives computer to post this question.) Other wise it should work fine.