Dragging from iMac to Macbook Pro

Question

I'm trying to copy some files between my iMac and Macbook Pro using Finder. The files are both owned by the same user, and I'm dragging between identically named folders. The files do NOT exist on the MBP when I start this operation.
When I try this operation, the first thing that occurs is that I am asked to enter my password, which has never occurred before (I just replaced my old Macbook with the MBP, which is the only change since I last tried to copy files from one system to the other). Okay, maybe this is due to the fact that the user numbers don't match (I'm user 501 on the iMac, user 503 on the MBP thanks to a Migration Assistant battle), so I go ahead and enter my password.
The next thing that happens is I get a dialog that says "A new item named "blah" already exists in this location. Do you want to replace it with the older one you're moving?" When I started the copy, "blah" did NOT exist on the MBP - it was created sometime after I began the copy. The file is empty on the MBP, so I click the Replace button.
I now get a new dialog that says "The operation can' be completed because an item with the name "" already exists." Note that the filename is apparently an empty string. At this point, I have no choice but to click OK. The copy is terminated, and I'm left with an empty file named "blah" on the MBP.

Answer 1

It turns out I can drag something from the remote system to the local system (i.e., Macbook Pro to iMac if I'm sitting at the iMac), but not from the local system to the remote system.