Can't detect external monitor

Question

I'm trying to plug a second monitor into my MacBook (13" aluminium - the MB version, not the MBP). The monitor is a 19" Iiyama, model PLE1900. I'm plugging in by DVI (DVI-D), using a Mini DisplayPort converter. The video on this laptop model is a NVIDIA GeForce 9400M.
When I plug in the monitor and turn it on, it just says "No Signal", but if I perform "Detect Displays" in the preferences, the monitor is detected, and even identified correctly.
So... I'm just stumped. Why would the lappy detect the display and then the monitor say "nothing here!"?
Is the problem due to DVI-D? The monitor also has a VGA (D-Sub) input, should I get a Mini DisplayPort adapter and try that? Obviously that an expense, so I'd rather not if I can help it.
Thanks for any replies.
Ben.

Answer 1

Ok,
It was neither the cable nor the computer (thanks Apple). It was the monitor's EDID profile. Dell's problem.
There's two ways to fix this. 1) It is possible (I did it) to create a custom profile using SwitchResX. You'll need to hook up your computer to the monitor using a working connexion (I used DVI) and then use the "export" function in SwitchResX. It will give you a text file. In it you'll have enough data to fill SwitchResX' form to setup a custom profile. You'll then need to restart the computer, hook it with the Displayport cable and try to use this custom EDID profile. It worked for me.
For example (and hoping it will help others) here are the data you need to setup a custom profile for the Dell 2408WFP :
Descriptor #0 - Timing definition:
Mode = 1920 x 1200 @ 59,950Hz
Pixel Clock............. 154,00 MHz Non-Interlaced
Horizontal Vertical
Active.................. 1920 pixels 1200 lines
Front Porch............. 48 pixels 3 lines
Sync Width.............. 32 pixels 6 lines
Back Porch.............. 80 pixels 26 lines
Blanking................ 160 pixels 35 lines
Total................... 2080 pixels 1235 lines
Scan Rate............... 74,038 kHz 59,950 Hz
Image Size.............. 519 mm 324 mm
Border.................. 0 pixels 0 lines
Sync: Digital separate with
* Negative vertical polarity
* Positive horizontal polarity
2) Of course, you can call Dell and tell them about it. They are sending me a THIRD replacement monitor for this. Be prepared when you call them : I spoke with two representative (and among them a "senior technician") who DIDN'T know what was a Displayport. They even tried to sell me the idea that 640x480 is the native resolution for Displayport. It was hilarious. Really. I got them to look it up on Wikipedia.
Case solved. Apple 1 - Dell 0.
P.