Question on Importing Leads: Lead Ownership

Question on Importing Leads: Lead Ownership

When I import a list of leads to a campaign from an excel spreadsheet, the lead ownership is assigned to me for every lead.  The spreadsheet contains a column called "Lead Ownership" and is mapped appropriately when I do the import.  All of names in the column are valid user names.  I import the file as "Import Organization Leads".  What am I missing?