Port forwarding error!!!!!

yesterday i was trying to configure a billion ISP provided router . i was trying to enable port forwarding to access a DVR over internet . Already we have a static ip which i tried to configure port forwarding but management wants the DVR to be accessed both in LAN as well as over the net.
even after configuring port forwarding we were not able to access the DVR on the net,i contacted the ISP helpdesk ,they asked me to use
DMZ ,even after enabling DMZ i was not able to access the DVR on the net.
Plz help me ,how can i access the DVR both on LAN and on the internet?

thanks in advance

I assume here that your DVR is already accessible through your LAN. Not sure what is DVR, what type of service is it? Any way I would consider the following:

1. Port forwarding should direct all inbound traffic coming into the billion router with a certain destination port to your DVR's private IP and port. Are you sure you've done this correctly? A screenshot of your router's interface might help us.

2. If you have a firewall before your DVR or at it, make sure you allow traffic from any IP.

3. Have you tried port forwarding to another server/IP? if it works, you will know that the problem is probably not with the billion router nor ISP.

Here is the setup
1. DVR is nothing but a Digital Video Recorder or a console attached to security cameras .A monitor can be attached to the DVR to get the security camera output.
2. DVR is connected to switch and assigned a ip 192.168.2.2 which is accessible in the LAN
3. our ISP connection is running with the static ip address ,which is also connected to the switch,all the systems are connected to the switch and they share the LAN and ISP.
4. we need to access the DVR from outside i.e in the internet using the static ip .how i have to configure the network in order access the DVR in the internet .
5.Also the DVR must be accessible in the LAN.

please help me!!!!!!!!!!!!!!!!!!!

Hmmm.. If you already have NAT or PAT setup to allow private to public IP translation, you may want to check your ACL in the firewall to make sure that the public IP your ISP assigned you, is pointing to the DVR device.

1.i access the DVR device in the LAN by using the local ip 190.168.2.2
2.I have enabled NAT in that ISP router.
3. Now i have to use the static ip address to access the DVR device over the internet ,
4. If i force the static ip in the DVR device ,it is not accesible in the lan.
but i can access over the internet.
5. i need to access the DVR device both in LAN and the internet.
plz help me techs

1.i access the DVR device in the LAN by using the local ip 190.168.2.2

Is this 190.168.2.2 or 192.168.2.2. I assume it's a typo.

2.I have enabled NAT in that ISP router.
3. Now i have to use the static ip address to access the DVR device over the internet ,
4. If i force the static ip in the DVR device ,it is not accesible in the lan.
but i can access over the internet.

What did you mean when you said "force the static ip" ? You already have a static ip 192.168.2.2 assigned for it!! You don't have to change it, you only have to configure the router to port forward (say port 80) to 192.168.2.2. Or am I missing it here?