External HD don't show from Mac to Mac

Hello
first time on this forum
I have two imac and I have some problems sharing External USB HD
I use External HD to store works every computer (3 PCs, 2 Macs)
has one external USB HD, and share that External HD on the network
the problem is between the two Imacs... I can a access all the external
HD from the PCs even the ones that I share from the IMacs, I already
share the external HD on the Imacs whit read and Write
Wen I conect from Mac to Mac I can only see the Internal HD
and the shared folder ...
I will post (If I can) images of my configuration)
so you can have a better view of the problem)
any help will be great.

thanks alot
Joss


Ps.. images
Links (I don;t nowk how to post it here)
the sistem is in spanish any Q, let me know)

http://img3.freeimagehosting.net/uploads/c8cd7dc194.png

http://img3.freeimagehosting.net/uploads/7c7d614923.png

http://img3.freeimagehosting.net/uploads/518e5e6a8e.png

http://img3.freeimagehosting.net/uploads/283b3f83f0.png

http://img3.freeimagehosting.net/uploads/ad2f3b3d44.png

http://img3.freeimagehosting.net/uploads/cb4b73faf2.png

http://img3.freeimagehosting.net/uploads/e0ffb72e08.png

http://img3.freeimagehosting.net/uploads/658bbc73eb.png

http://img3.freeimagehosting.net/uploads/546e0f9cca.png