I just looked into your file (.qvf)
you are using the Data Manager and not the script editor
in the Schema I found that the two tables are related via the common field "Date Combined"
now if you want to link the two tables via the 2 columns Project and Date Combined, then both tables should have the same field name for the project
but keep in mind that when two tables have more than one column in common then synthetic keys will be created and this is not recommended in qlik so you have to create composite key in both tables like Project & '|' & DateCombined as key