Sumif WorksheetFunction On Array

does the SUMIF worksheetfunction in VBA work on Arrays? I know it will work on ranges, and thats all fine, but I am convinced it should work on an array too... for example... Just assume two columns of numbers (A and B) with 13 rows -

Public Sub test()
Dim a As Range, b As Range
Dim x, y
x = ActiveSheet.Range("A1:A13").Value
y = ActiveSheet.Range("B1:B13").Value
Set a = ActiveSheet.Range("A1:A13")
Set b = ActiveSheet.Range("B1:B13")
MsgBox Application.WorksheetFunction.Sum(x) 'works
MsgBox Application.WorksheetFunction.Sum(y) 'works
MsgBox Application.WorksheetFunction.SumIf(x, "1", y) 'wont work - "Object Required"
MsgBox Application.WorksheetFunction.SumIf(a, "1", b)
End Sub

I also tried Transposing the x and y arrays, but the same result "Object Required".