Thank you for your post, and I apologize for the late reply.
Instead of using Admin Console to upload the database file, go into Windows and copy the file manually to the destination folder. If this works, make sure the path used to copy files in the Admin Console is correct. If this fails, then make sure there is enough room on that drive.
If you have since found the cause, please post the answer here so others who encounter this problem have a possible solution.