How to fix a syntax error?

Question

Visual Basic

I'm trying to add codes from a list to another table. Since you need to enter all the elements, I use a loop:

Private Sub save_marks_Click()
Dim strSQL As Variant
For Each strSQL In criteria.ListIndex
strSQL = " Insert Into marks(userid, finalgrade, criteriaid) values ('" & Me.student & "', '" & Me.mark & "', '" & Me.criteria & "');"
CurrentProject.Connection.Execute (strSQL)
Next strSQL
MsgBox ("Added!")
End Sub

It gives an error that For Each is only for objects and arrays. Tell me how to implement correctly?