Object reference not set to an instance of an object.

Sub Activation()
           Dim activationKey As String = Date.Now.Millisecond * Date.Now.Second * 3 * Year(Now) + Date.Now.Day * 77 'Generates Activation Key
           Try
               strCon = System.Configuration.ConfigurationManager.AppSettings("ConnectX").ToString()
           strQry = "Insert INTO tActivation (sUsername,ActivationCode,ActivationStatus,DateRegistered,DateActivated,AccountEmail) Values('" & userID & "','" & activationKey & "','" & 0 & "','" & Now & "','" & Now & "','" & txtEmail.Text & "')"
               cn = New SqlConnection(strCon)
               cn.Open()
               Com = New SqlCommand(strQry, cn)
               Com.ExecuteNonQuery()
               Com.Dispose()
               cn.Close()
               SendToMail(activationKey) 'Calls a Procedure to send the key using SMTP server


           Catch ex As Exception

       End Try
       End Sub