I found out by doing via vlookup instead of dictionary.

However, if you know the answer via dictionary, I'd like to learn too.

Below is the code that I've done via vlookup

For Each profitCentre In myProfitCentreArray
    If profitCentre <> "" And Not profitCentre Like "####0000" Then
    With Workbooks(wbPropListing).Sheets("Residential")
       Set lookupResRange = .Range("E3:F" & .Cells(Rows.Count, "E").End(xlUp).row)
    End With
    With Workbooks(wbPropListing).Sheets("Fund&CoT")
       Set lookupFundRange = .Range("E2:F" & .Cells(Rows.Count, "E").End(xlUp).row)
    End With

    lookupResult = Application.VLookup(CStr(profitCentre), lookupResRange, 2, False)
    If IsError(lookupResult) Then
       lookupResult = Application.VLookup(CStr(profitCentre), lookupFundRange, 2, False)
       If IsError(lookupResult) Then MsgBox "Profit Centre: " & profitCentre & " Not Found"
       End If
    myforecastSheetsIndex = myforecastSheetsIndex + 1
    End If
Next profitCentre