Public Function GetFilesByDate(ByVal folder As String, _
                         ByVal criticalday As Date) As List(Of String)
 
   Dim filenames As New List(Of String)
 
   For Each fi As IO.FileInfo In New IO.DirectoryInfo(folder).GetFiles
      If fi.CreationTime.Date = criticalday.Date Then
         filenames.Add(fi.Name)
      End If
   Next fi
 
   Return filenames
End Function

lbo.DataSource = GetFilesByDate("C:\daten", CDate("20.04.2016"))