Populate Various Comboboxes by Function Call - vba

Question

Morning !
I'm trying to make my code more generic by using Functions to populate various ComboBoxes, however, I'm with troubles to do this...
In UserForm:
Private Sub UserForm_Initialize()
Call Lista_Vendedores
ComboBox1.List = Lista_Vendedores
End Sub
In Module:
Public Function Lista_Vendedores() As Variant
Dim Lista As New Collection
Dim Cont_Vendedores As Integer
Cont_Vendedores = Plan1.Cells(1, 8).Value
Sheets("Plan1").Select
For i = 3 To Cont
Lista (Row.Cells(i, 8))
MsgBox Lista
Next i
Set Lista_Vendedores = Lista
Set Lista = Nothing
End Function
When I try to run the code, nothing happens, however, none error is shown.

Answer 1

Your code can be simplified a lot. It doesn't need to be in a function, just give it a range as per the example below:
Userform:
Private Sub UserForm_Initialize()
ComboBox1.List = ThisWorkbook.Worksheets("Sheet1").Range("A1:A8")
End Sub
Module:
Public Sub ShowUserform()
UserForm1.Show
End Sub

Answer 2

You are making lots of mistakes in your code, and while CallumDA33 solution is better, I think you should take a look at this:
First, you are not calling your function correctly. The sub should be:
Private Sub UserForm_Initialize()
ComboBox1.List = Lista_Vendedores
End Sub
The Call line is not necessary. (and the keyword Call itself is almost never required). I really don't get where your syntax is coming from.
In the Lista_Vendedores function, you are not using correctly the Lista Collection.
Cont is undefined. You should always use Option Explicit at the start of your modules.
You are not affecting any value to the collection.
You should also avoid using Select as much as possible.
The List property expect an variant array, not a collection, so the function should return a variant array, not an variant containing a single (empty) collection object, so I also changed the type for Lista.
Follows corrected but untested code:
Public Function Lista_Vendedores() As Variant()
Dim Lista As Variant()
Dim Cont_Vendedores As Integer
With Sheets("Plan1")
Cont_Vendedores = .Cells(1, 8).Value
Redim Lista(0 to Cont_Vendedores-3)
For i = 3 To Cont_Vendedores
Lista(i-3) = .Cells(i,8)
Next i
End With
Lista_Vendedores = Lista
End Function
Edit: corrected typo