You should do something like...
VB Code:
  1. 'Behind search form

  2. Private Sub frmSearch_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing

  3.     Me.Hide()

  4.     otherform.Show

  5. End Sub

  6.  
  7. 'Behind main form

  8. Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click

  9.     ShowFormSelect(sender, e)

  10.     Me.Hide

  11. End Sub