For each individual you have added to Lost Cousins, FT Analyser is expecting to find in your GEDCOM file the following snippet of information

    2 TYPE Lost Cousins 
    2 DATE yyyy

Where yyyy is one of 1841, 1881 or 1911, the three years that LC supports from the UK Census. (The above snippet is indented only to improve readability.)

The individual guides will provide more detail on how to achive this with each product