MacBook Pro cannot see WD External Hard Drive that is connected to my iMac

Here's the issue at hand...I just got an iMac and connected my external WD Hard Drive to it. I can see it perfectly through the iMac. However, my Macbook Pro which is connected wirelessly through the same network cannot see the external hard drive. When I go to Finder (on the MBP), under Shared, I see the iMac and when I connect as a Registered User, I see Macintosh HD and my username, but again, no external HD. Can someone please tell me what I may be doing wrong?
I did setup File Sharing on the iMac to share the WD Hard Drive. Thank you in advance.