[ubuntu] VirtualBox sharing folder between host (ubuntu) and guest (redhat) machine

I am using Ubuntu 12.04 as my host machine and trying to share a folder with my guest machine which runs Redhat Enterprise Linux 5.

I have already installed VirtualBox Additions. Now when I try to run my following command :
it keeps showing me the error of
I have been searching on net but most of the solutions are for guest machines as ubuntu not redhat (I was thinking it wount cause a problem but i tried the solution of ubuntu it didnt work)

Thanks in advance.

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