Ok vb code for User Form does not work, it save data info wrong

I'm having trouble with my user form. When I enter new data and save it, the surname doesn't get copied to column Z like it's supposed to.
Even when I add a new main member and two other members, the surname still doesn't copy to column Z. Then, if I add another new main member and members,
it replaces the first non-main member and adds the new members below it, so I end up losing the two members I added before.
It seems like there's an issue with copying the surname to column Z.

Private Sub btnOK_Click()
    Dim ws As Worksheet
    Set ws = ThisWorkbook.Sheets("Register") ' Change "Register" to the name of your sheet
    
    ' Find the next empty row in the sheet
    Dim nextRow As Long
    nextRow = ws.Cells(ws.Rows.Count, "A").End(xlUp).Row + 1
    
    ' Write data to the sheet
    With ws
        ' Column A and B (automatically inserted)
        .Cells(nextRow, 1).Value = "Some Value" ' Example value for column A
        .Cells(nextRow, 2).Value = "Some Value" ' Example value for column B
        
        ' Column C (Surname)
        .Cells(nextRow, 3).Value = Me.txtVan.Value ' Value from txtVan textbox
        
        ' Copy the surname to each member's row (Column Z)
        For i = 1 To 5
            If Not IsEmpty(Me.Controls("txtNaam" & i).Value) Then
                .Cells(nextRow + i - 1, 26).Value = Me.txtVan.Value ' Copy surname to column Z
            End If
        Next i
        
        ' Columns D to I (Names, Birthday, Anniversary, Home Tel, Work Tel, Cell Numbers)
        For i = 1 To 5
            If Not IsEmpty(Me.Controls("txtNaam" & i).Value) Then
                .Cells(nextRow + i - 1, 4).Value = Me.Controls("txtNaam" & i).Value ' Name
                .Cells(nextRow + i - 1, 5).Value = Me.Controls("txtVerjaar" & i).Value ' Birthday
                .Cells(nextRow + i - 1, 9).Value = Me.Controls("txtselfoon" & i).Value ' Cell Number
            End If
        Next i
        
        ' Column J (Address)
        .Cells(nextRow, 10).Value = Me.txtadres.Value ' Address
        
        ' Anniversary, Home Tel, Work Tel
        .Cells(nextRow, 6).Value = Me.txthuwelikdatum.Value ' Anniversary
        .Cells(nextRow, 7).Value = Me.txtHuis.Value ' Home Tel
        .Cells(nextRow, 8).Value = Me.txtWerk.Value ' Work Tel
    End With
    
    ' Clear input fields after saving
    Me.txtVan.Value = ""
    For i = 1 To 5
        Me.Controls("txtNaam" & i).Value = ""
        Me.Controls("txtVerjaar" & i).Value = ""
        Me.Controls("txtselfoon" & i).Value = ""
    Next i
    Me.txthuwelikdatum.Value = ""
    Me.txtHuis.Value = ""
    Me.txtWerk.Value = ""
    Me.txtadres.Value = ""
    
    ' Close the UserForm
    Unload Me
End Sub