Problem with SAP logon by VBA

Hi, I'm new in the community and I'm also new with SAP, so sorry for any errors.

For my work I need to open SAP by excel (VBA); and I have found the code below but it don't work.

Sub Work()

Set app = CreateObject("Sapgui.ScriptingCtrl.1")

Set Connection = app.openconnection("my system", True)

Set session = Connection.Children(0)

session.findById("wnd[0]/usr/txtRSYST-MANDT").Text = "Client"

session.findById("wnd[0]/usr/txtRSYST-BNAME").Text = "User"

session.findById("wnd[0]/usr/pwdRSYST-BCODE").Text = "Password"

session.findById("wnd[0]/usr/txtRSYST-LANGU").Text = "Language"

Session.findById("wnd[0]").sendVKey 0

End Sub

When the macro runs there is this error  

Can you help me?

Thank you,

ax_salerno