Data Shuttle Mapping Issues

Hi,

I am trying to setup a data shuttle to replace data in a sheet using the most recent SS attachment in another sheet. I have used Data Shuttle many times and not sure why this time it is not working. The columns in the SS match the columns in the excel attachment. When I get to the "mapping" section of the configuration it does not auto map the columns with the same names it just gives me "column A", "column B", etc. Has anyone come across this issue and know how to fix it? Thanks!!