ExcelToCI Load with blank keys that are not required

I am trying to load two tables BN_RATE_TBL and BN_RATE_DATA using ExcelToCI.  BN_RATE_DATA has 5 key fields RATE_TBL_ID, EFFDT, BN_RATE_KEY01, BN_RATE_KEY02, BN_RATE_KEY03.  I can add a new rate id using Create and a I can add a new effdt row using Update but I cannot update an existing row of data when BN_RATE_KEY01, 02 AND 03 are blank.  The component allows these key fields to be blank when the rate type = 2, Flat Rate Table.  When I try to update an existing row that has those these key fields blank, I get "No key match was found for collection BN_RATE_DATA".