Getting information about rejection of RFC logon

Dear community,

we use a Visual Basic program to connect to SAP for doing funny things.

The connection is opened via RFC in this style:

(like published here and found at many other places in the SAPnet and internet)

If oBAPICtrl.Connection.Logon(frmStart.hWnd, False) = False Then
  MsgBox "R/3 connection failed"
  End
End IfThe call of .Connection.Logon returns True/False only. But - in professional programming - I need to tell the reason WHY the connection was refused. There are so many possibilities (from wrong password to system not reached).

So, can anyone tell me how to retrieve any sort of further information? Can't believe it is not possible...

Thank you for the help.

Michael