drivers - AMD Catalyst Installation on Ubuntu; No supported adapters detected

I'm trying to install AMD Catalyst on my Linux Mint 17 (Ubuntu 14.04) OS.

My notebook has switchable graphics, Intel HD 3000 and Radeon HD 7550M.

Following lots of instructions here and other blogs, I was able to install Catalyst 14.9. (link to instruction)

But following command gave me "amdconfig: No supported adapters detected":

sudo aticonfig --initial --adapter=all

Here is the output of lspci | grep VGA:

00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7550M/7570M/7650M] (rev ff)

fglrxinfo output:

OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel® Ivybridge Mobile
OpenGL version string: 1.4 (3.0 Mesa 10.1.0)

/etc/rc.local file:

sudo chmod -R 705 /sys/kernel/debug
sudo chown -R MYUSERNAME:MYUSERNAME /sys/kernel/debug/vgaswitcheroo
echo ON > /sys/kernel/debug/vgaswitcheroo/switch

And /etc/default/grub:

…
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
…

How to solve this?

First change to discrete card by using this code:

sudo amdconfig --px-dgpu

Then do this:

sudo amdconfig --initial -f

Reboot.

Also you can activate trusty-proposed and try to install fglrx.