Problem encountered when adding calculated item into pivot tabe

An extract of my source file is attached Source file_Pivot table.PNG

Pivot table was created with:

Row Labels: Region/Name
Column Labels: Version
Data: Sum of the values

A calculated item was added to find the variance between FY1415 and FY1516. When this calculated item is added, the pivot table rows were populated with all the rows, e.g. Region EU should be displaying Station 5 and 6 only but now, Station 1 to 4 get populated into the Pivot Table. See sample of the Pivot Table below.

Would like to know how to get around this issue? I would like to have the flexibility of adding the calculated item but not the unnecessary rows. Thanks,

Pivot table.PNG