A function declared Private in VBA Module doesn't run on UserForm. Error
reads: Sub or Function not defined.

Function:
Private Function IncomeTax(salaryGross, children, spouse) As Double
Application.ScreenUpdating = False
Call objectVarDeclare

Dim dblChildAmount As Double
Dim dblSpouseAmount As Double
Dim dblTaxAmount As Double
Dim dblTaxNet As Double
Dim rngTaxOne As Single
Set rngTaxOne = salarios_data.Range("tax1")
Dim rngTaxTwo As Single
Set rngTaxTwo = salarios_data.Range("tax2")
Dim rngMinSalary As Range
Set rngMinSalary = salariosData.Range("upper_first")
Dim rngFirstTier As Range
Set rngFirstTier = salarios_data.Range("upper_second")
Dim rngChildCredit As Range
Set rngChildCredit =
salarios_data.Range("child_credit")
Dim rngSpouseCredit As Range
Set rngSpouseCredit = salarios_data.Range("spouse_credit")

dblChildAmount = 0
dblSpouseAmount = 0
dblTaxAmount = 0
If salaryGross <= minSalary Then
dblTaxAmount = 0
IncomeTax = 0
dblChildAmount = 0
dblSpouse_amount = 0
ElseIf salaryGross minSalary And salaryGross <= rngFirstTier Then
dblTaxAmount = ((salaryGross - minSalary) * rngTaxOne.Value)
Select Case children
Case Is 0
dblChildAmount = children * rngChildCredit
Case Is = 0
dblChildAmount = 0
End Select
Select Case spouse
Case Is 0
dblSpouseAmount = spouse * rngSpouseCredit
Case Is = 0
dblSpouseAmount = 0
End Select
If dblChildAmount + dblSpouseAmount = dblTaxAmount
Then
IncomeTax = 0
Else: IncomeTax = dblTaxAmount - dblChildAmount - _
dblSpouseAmount
End If
ElseIf salaryGross rngFirstTier Then
dblTaxAmount = ((rngFirstTier - rngMinSalary) * rngTaxOne.Value) + _
((salario - rngFirstTier) * rngTaxTwo.Value)
Select Case children
Case Is 0
dblChildAmount = children * rngChildCredit
Case Is = 0
dblChildAmount = 0
End Select
Select Case spouse
Case Is 0
dblSpouseAmount = spouse * rngSpouseCredit
Case Is = 0
dblSpouseAmount = 0
End Select
If dblChildAmount + dblSpouseAmount = dblTaxAmount Then
IncomeTax = 0
Else: IncomeTax = dblTaxAmount - dblChildAmount -
dblSpouseAmount
End If
End If
End Function

In UserForm's OnChange event of ListBox of names of employees:
sngTaxNet = IncomeTax(rngGrossSalary.Offset(intIndex + 1, 0), _
rngChildren.Offset(intIndex + 1, 0), rngSpouse.Offset(intIndex + 1,
0))


Any way to make it work? Any mistakes made writing the code?

Thanks in advance.

Oscar