The reason that abc is showing up is because the measure is on the level of detail shelf, move it to the Text shelf. So you want to see the difference in revenue from the previous week, but start with last week as opposed to this week? One way would be to filter the date so that only those two weeks are showing. Then, add the table calc.
If you want it to be more dynamic a calculated field similar to the following could be created and placed on the filter shelf:
dateadd('week',-2,today())<=[Order Date] and dateadd('week',-1,today())>=[Order Date]
Hope this helps!