EAD/CSV Importer - "Import Error: Invalid CSV FIle"

We just installed the EAD Importer and tried to upload an EAD file. The plug-in said that this was successful, but when we went to the CSV Import tab, under status, it said "Import Error: Invalid CSV FIle".

I was wondering what could cause this? The only thing we weren't sure of when uploading the ead file into the ead importer was the "Filter by String" field, so we left that blank. Could that cause this error?

Thanks in advance!!