Got new monitor, but not getting any Video Output.

Hi I just bought this new 2494HS Samsung screen (23.6"), but I'm not getting any video output when I start my computer. I connected it with DVI and VGA, but none work. You can only see it keeps checkinkg signals from "HDMI", "Analog" and "Digital" but no video output....I'm getting very very frustrated now, wasted 2 hours on it now, and having headache, can someone please help me out?...

Thanks

EDIT: I've also used my other laptop to send signal to the new monitor, but it doesn't notice the screen, when I use my old monitor, it directly finds it. Weird thing now also is that when I connect my old monitor to my desktop, like it used to be, it doesn't find it either anymore...Looks like my desktop AND the new monitor are broke now...
This is getting a mess, can anyone please help out?

EDIT: Never mind, old monitor gets signals from desktop and laptop now, but new monitor doesn't get signal from both...Am I doing something wrong or what....Tried DVI IN and RGB IN, but also doens't make difference...

check the DVI cable connection to your monitor (as in, the socket on the monitor) to see if it is connected properly. if that doesn't work, yank the VGA/DVI cable from your old monitor, plug it into the new one, and see if it works. if that doesn't work, maybe the monitor is defective. bring it back to the store (i'm assuming you bought it at a store here) and let them try it. if it is broken, just ask for a replacement.

Well, I'm unable to use the VGA-cable of the other monitor, it's a 10+ year old monitor, you are unable to pull it out. But I called store and going to bring it back on monday, it has to be defective I guess, tried everything..

Thanks

Ok, small update:

My dad brought the monitor back to the store, some guy tested it (without my dad seeing it) and he said everything worked fine...I just can't believe it we tried every possible thing with the monitor to see what could be the problem, tested it with 2 different VGA cables, and another DVI cable, also tested it on 2 more different laptops and this desktop, and also connected this old monitor to the old laptops, and those got signals, but when we connected the new monitor it said "Check Signal", on both. The guy said that it could be compatiblity problems, but I never heard of that with monitors....I have 6-year old computer with Windows XP (shouldn't be the problem I think), nothing upgraded except the Graphics Card, which is a GeForce 8600GT. The new monitor was a Samsung 2494HS. I can't test it now anymore my dad left it at the store and got a coupon back...Do you guys know what could be the problem, except that the thing is defective, and the guy at the store didn't really check it (which I think). The screen did turn on, and you could change source (it has 3 connections, HDMI, DVI and VGA) but other than that nothing got through, no signal from computer. I'm just wondering if I should just get another 2494HS because it could've been a defective monitor, or if my computers (I tested it on 3) are all non-compatible with it...Which I can hardly believe.

Thanks

It can sometimes happen that if the monitor isn't turned on when the PC boots - the BIOS or the video card doesn't read the monitors info properly and so wont initialise the monitor or the card output.

I have this happen with my KVM and my older machine - if the KVM isnt connecting the monitor to that PC when I turn it on, then the display won't work - once the PC is booted I can switch away to the other machine and let windows start. Your problem sounds something like this - and it may only be solvable ultimately with a different video card.

In between - if your Dad will try again, make sure in BIOS that the video card has priority when booting and try also turning off any quick boot features so that the PC does things the old fashioned (and slightly more reliable) way of detecting connected devices.

Ok thanks Lyndka. I'll keep you up-to-date if my dad wants to try again...I hope so :/.