Using a Macro as a Function Called From Cell to Populate a Cell Value

Using a Macro as a Function Called From Cell to Populate a Cell Value

I'm trying to populate individual cells with  function calls to a macro similar to how one would use a regular function to populate a cell. My function is:

Public Function getHours(item As String,high As Number) As Double
    Sheets("Work Items").Select
    numRows = ActiveSheet.Rows
    getHours = 0

    For i = 2 To numRows
        if Cells(i,2).value= item Then
            if high = 1 Then   
                getHours = getHours + Cells(i,6).value
            else
                getHours = getHours + Cells(i,5).value
            end if
          end if
    Next i
End Function      

Where I pass a cell value and constant to return a double. However, whenever I try to use the function, it doesn't come up as an option when I type = into the cell, and when I type out the arguments like "=getHours(a3,0)", it re-formats to "=GETHOURS(A3;0)" and gives me a #NAME! error. Even if my code isn't correct, it doesn't seem like using macros in this fashion even works in Sheet.

My function doesn't show up on the manage tab for macros, but when I try to create a new macro with the same name it says that it already exists.

If using a macro isn't possible, could I be assisted with an alternative method?

Thanks.