Search the forum for NEW, LOST, RETURNING customers, it seems you want to show something like this.
There are multiple approaches, if you want to compare fixed periods, you can also try set analysis: For example, to show outlets that had no sale in max month but sale in max month -2, something like
=Count(
{<[DMS Outlet Code] =
e({<InvMonth = {"=InvMonth=$(=Max({1}InvMonth))"}>})*p({<InvMonth = {"=InvMonth=$(=Max({1}InvMonth))-2"}>} )
>}
DISTINCT [DMS Outlet Code])
