Filter & Mapping Option not availabale in Data Shuttle


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 "filter" section of the configuration, It is not showing me the available columns for selecting the one on which filter is to be applied. Moreover, it is not showing the columns in mapping section to auto map the columns with the same names. Please note that I have correctly added my source file in the "Source" section.