UR28M Gain and guitar issue.

I have latest cubase 6,51 and the latest Soundcard driver for Ur28M.
Tried it on windows 7 and it worked well.

Now i just got my self a iMac of biggest model mid 2011. with Lion OS.
The problem is when i play the guitar and turn the gain all the way down, i still hear the guitar with high sound.
And it sometimes sounds like there is 2 guitar sounds at the same time.
When i use the gain there is not much difference.
I can even play the guitar without logging into Cubase.

When i used windows 7 i could turn the guitar off when i used the gain.

Isn’t it suppose to be same on mac and windows?
Or does it sound like its normal?
Anybody got the same problem ?

All drivers are the latest and i followed the steps on installation of the sound card

Best regards Bingus