HELP!! Why can't I use more than 2 GPUs in my Linux?

[Kenshin]

Why can't I use more than 2 GPUs in my Linux? I tried and installed xubuntu, I also installed the amd driver and amd APP SDK.

I have 4 GPUs, but cgminer can only see 2. Am I missing something?

cgminer --scrypt -o stratum+tcp://stratum2.wemineltc.com:3334 -u username.1 -p password -I 20

Do I need to do that any hardware hacking for the monitor plug? I haven't done that is that what is missing?

I also got this error:

 [2013-11-17 19:26:15] Use the gpu map feature to reliably map OpenCL to ADL
 [2013-11-17 19:26:15] WARNING: Number of OpenCL and ADL devices did not match!
 [2013-11-17 19:26:15] Hardware monitoring may NOT match up with devices!

How do I fix this?
help thanks.

[sveetsnelda]

This belongs in the mining support forum.

What does "sudo aticonfig --list-adapter" show?  Are all four cards listed?

[Kenshin]

This belongs in the mining support forum.

What does "sudo aticonfig --list-adapter" show?  Are all four cards listed?

Thanks. I solved it. After following this guide: http://www.cryptobadger.com/2013/04/build-a-litecoin-mining-rig-linux/