VBA SumIfs not working - Expenses management tool in Excel 2007

[NadCu42]

Hello,
I'm trying to build an expenses management tool in Excel 2007. The main sheet should scan the app directory for another xls_ files and extract my expenses data from them. I wrote this VBA code for the data import:

Public Function sumMonthExpenseByCategory(ByVal istr_WbFilename As String, _
                                      istr_expenseCategory As String)    ' for example: "Insurance"
    
    Dim str_FileName               As String
    Dim rng_SumRange            As Range
    Dim rng_ConditionRange     As Range
    Dim rng_CurrRange            As Range
    Dim wb_Source                As Workbook
    Dim o_ExcelApplication      As Excel.Application

    Set o_ExcelApplication = New Excel.Application    
    o_ExcelApplication.ScreenUpdating = False

    ' Opening the Source Excel workbook in ReadOnly mode:
    str_FileName = getAppPath & istr_WbFilename

    Set wb_Source = o_ExcelApplication.Workbooks.Open(str_FileName, , True)
    
    If Not wb_Source Is Nothing Then
        Set rng_SumRange = wb_Source.Sheets(1).Range("Sum")
        Set rng_ConditionRange = wb_Source.Sheets(1).Range("Category")
        sumMonthExpenseByCategory = o_ExcelApplication.WorksheetFunction.SumIfs(rng_SumRange, rng_ConditionRange, istr_expenseCategory)     ' Should be: 163.25

    ' Closing the source workbook:
    wb_Source.Close False             ' Not saving the file when closing it
    Set wb_Source = Nothing
    
    End If

This is my expense data from my credit card provider (I'm Israeli, so for this thread I manually translated the values to simple examples in English):
(I'm writing on my PC at work so I cannot download any addins for formatting tables and also I cannot seem to paste this table correctly... )

date expense text Sum currency Category
22/12/2015 restaurant #1 42 ₪ Lunch at work
23/12/2015 restaurant #2 42 ₪ Lunch at work
24/12/2015 restaurant #3 58 ₪ Lunch at work
27/12/2015 restaurant #4 38 ₪ Lunch at work
28/12/2015 restaurant #5 50 ₪ Lunch at work
29/12/2015 restaurant #6 38 ₪ Lunch at work
30/12/2015 restaurant #7 40 ₪ Lunch at work
31/12/2015 restaurant #8 46 ₪ Lunch at work
12/11/2015 life insurance 101.5 ₪ Insurance
28/12/2015 health insurance 61.75 ₪ Insurance
14/12/2015 gas for car 187.7 ₪ Gas
27/12/2015 gas for car 196.35 ₪ Gas
15/12/2015 parking near home 22 ₪ Parking
16/12/2015 parking near work 6 ₪ Parking
27/12/2015 parking near mall 33 ₪ Parking
30/12/2015 parking at girlfriend's 55 ₪ Parking
01/03/2016 Tel Aviv muni 557.41 ₪ City bill
30/12/2015 Electra Ways inc. 644.63 ₪ Electricity bill
30/12/2015 Spring Water inc. 71.1 ₪ Water bill
30/12/2015 Haaretz magazine ltd 196 ₪ Newspaper

I'm succeeding in opening the file and I get the data ranges, but the SUMIFS function always return 0.
Can anyone figure out why is that so?

Thank you very much!