If statement with Set analysis to select prior year ignoring periods graph

[#1]

I have the following expression :

i have 3 items in VersionSelect...they are Budget;Forecast;Last_Year

when i select either Budget or Forecast, my graph shows all periods (as i assume my set analysis below tells it to ignore all periods).

the issue is when i select "Last_Year".

for some reason, it does the second part of the "If" statement, but it no longer ignores the period selection and only returns the period selected on the graph.

can someone help with this?

thanks

=if(VersionSelect <> 'Last_Year',

Sum({$<Input_Sheet = {"TMOS"},

    Obj_# = {"*"},

    KPI = {"Total circulation revenue (£m)"},

    KPI_Definition = {"*"},

    Owner = {"*"},

    BU = {"TMOS"},

    Level = {"*"},

    Data_Contact = {"*"},

    Data_Source = {"*"},

    Period = {"*"},

    YTD = {"*"},

    CurPd = {"*"}>} $(vComp_Version)),

Sum({$<Input_Sheet = {"TMOS"},

    Obj_# = {"*"},

    KPI = {"Total circulation revenue (£m)"},

    KPI_Definition = {"*"},

    Owner = {"*"},

    BU = {"TMOS"},

    Level = {"*"},

    Data_Contact = {"*"},

    Data_Source = {"*"},

    Year = {$(#=Only(Year)-1)},

    Period = {"*"},

    YTD = {"*"},

    CurPd = {"*"}>} Actual))