Get values from collection in one module into combobox in userform - vba

Question

I have a worksheet with data in column 'EGM'. My code saves values from this column in the collection.
If there is only one value in the collection, then variable sSelectedEGM is equal to this value.
But if there is more than one values, a user should has possibility to choose only one value (I wanted to do this in the combobox) and save selected item into variable sSelectedEGM.
My problem is, that I can't get values from this collection into userform.
When my code go into useform, the error "Type mismatch" appear. My code in worksheet:
Public sSelectedEGM As String
Public vElement As Variant
Public cEGMList As New VBA.Collection
Sub kolekcjaproba()
' ===================================
' LOOP THROUGH EGMS AND WRITE THEM INTO COLLECTION
' ===================================
Dim iOpenedFileFirstEGMRow As Integer
Dim iOpenedFileLastEGMRow As Integer
Dim iOpenedFileEGMColumn As Integer
Dim iOpenedFileEGMRow As Integer
Dim sOpenedFileEGMName As String
Dim ws As Worksheet
Dim wb As Workbook
Set wb = ThisWorkbook
Set ws = wb.Worksheets(1)
iOpenedFileFirstEGMRow = Cells.Find("EGM").Offset(1, 0).Row
iOpenedFileLastEGMRow = ActiveSheet.Cells(ActiveSheet.Rows.Count, iOpenedFileFirstEGMRow).End(xlUp).Row
iOpenedFileEGMColumn = Cells.Find("EGM").Column
For iOpenedFileEGMRow = iOpenedFileFirstEGMRow To iOpenedFileLastEGMRow
sOpenedFileEGMName = Cells(iOpenedFileEGMRow, iOpenedFileEGMColumn).Value
For Each vElement In cEGMList
If vElement = sOpenedFileEGMName Then
GoTo NextEGM
End If
Next vElement
cEGMList.Add sOpenedFileEGMName
NextEGM:
Next
If cEGMList.Count = 1 Then
sSelectedEGM = cEGMList.Item(1)
ElseIf cEGMList.Count = 0 Then
MsgBox "No EGM found"
Else
Load UserForm1
UserForm1.Show
End If
End Sub
And my code in a userform (There is only a combobox on it)
Private Sub UserForm_Initialize()
For Each vElement In cEGMList
UserForm1.ComboBox1.AddItem vElement
Next vElement
End Sub
Private Sub ComboBox1_Change()
If ComboBox1.ListIndex <> -1 Then
sSelectedEGM = ComboBox1.List(ComboBox1.ListIndex)
End If
End Sub

Answer 1

you have to declare cEGMList and sSelectedEGM in a standard module as public and not in a worksheet module.
Or even better: create a property on the form for the collection and for the returned values. It's always better to avoid global vars wherever possible.
This is a simplified example. In the form you can define properties and methods like that:
Option Explicit
Public TestProperty As Integer
Public Sub TestMethod()
MsgBox (TestProperty)
End Sub
Public Function TestMethodWithReturn() As Integer
TestMethodWithReturn = TestProperty * 2
End Function
outside the form you can then use this as a normal property/method of the form:
Private Sub Test()
Dim retValue As Integer
UserForm1.TestProperty = 123
UserForm1.Show vbModeless
UserForm1.TestMethod
retValue = UserForm1.TestMethodWithReturn
Debug.Print retValue
End Sub