Trigger not working

[bk_raavi]

I have written a trigger to Prevent logon from a Computer with IP address 10.3.35.104
But this trigger is not working .

Create or replace trigger test
After logon on Schema
Begin
if sys_context('USERENV','IP_ADDRESS') = '10.3.35.104' then
raise_application_error(-20000,'U have no rights to Logon');
End If;
End ;