it must be to do with the cable you're using. if you're using hdmi out from the laptop (the hdmi real connection) the other end must be hdmi too that means your lcd screen must have an hdmi input, some monitors and laptops only work that way.
I'd suggest to use dvi or vga cable without any converters or adaptors,,and see
what happens, also did you try another monitor? a friends, neighbor ect..