I had a similar problem as kas_27_es, and just wanted to post to add my thoughts.
I would first test if pkremote can connect to the camera when running as root, ie: sudo pkremote
That worked for me, though it's not the best idea to have to run it as root. So I ended up editing the rules file changing "DIGITAL_CAMERA" to "DSC_K20D", and also appending
Code:
, OWNER="your_username_here"
after restarting udev this ended up working for me
I'm not sure why adding my user to the plughw group didn't work, but I am by no means knowledgeable about these things and my solution was sufficient for me.