ByRef argument type mismatch - problem wint function

[kmeld]

Hi,
I have a problem with function and sub using this function. Everything work if I use value of argument (integer in this case) and gives and ByRef argument type mismatch if I try to use integer variable.

situation is as follows:
I have a public function in ThisWorkbook:

Public Function SprawdzNumer(g As String, num As Integer) As Integer
....
end function

This function works.

Than in user form I have sub that uses this function. This sub is than used by various controlls.

Sub SprawdzNumer()

If Not numer = 0 Then

    If Dodanie_nowego.Combo_grupa.ListIndex > -1 Then

    
        Dim i As Integer
        
        i = ThisWorkbook.SprawdzNumer("I", 500)
    
        If i = 1 Then
            MsgBox ("Numer już występuje. Proszę podać inny lub wybrać opcję 'AUTO'")
            Dodanie_nowego.Text_numer.Value = vbNullString
            numer = 0
        ElseIf i = -1 Then
            MsgBox ("Nieprawidłowy symbol grupy")
        End If
    
    End If

End If
' ElseIf Len(Dodanie_nowego.Text_numer.Text) < 1 Then
   
End Sub

as you can see in the line :

        
        i = ThisWorkbook.SprawdzNumer("I", 500)

I had put values "I" and 500 (now they are static to avoid problems).

Than in one of control buttons I call SprawdzNumer sub. and that is where I got error.

Private Sub CommandButton1_Click()
MsgBox ("Numer: " & numer)
MsgBox (ThisWorkbook.SprawdzNumer("I", numer))

End Sub

numer is integer variable declared in this userform. Its value is 500 (for tests).

If I run the same code only not using numer variable but value of 500 I got no errors.

What is wrong?

Cris