Audit trail does not show user login events

Steps:
1. Installed Alfresco Community 4.0.e
2. Enabled auditing by adding the following in alfresco-global.properties
audit.enabled=true
audit.alfresco-access.enabled=true
3. Start the server
4. Login to Alfresco Explorer
5. Verify auditing is enabled with

curl -u admin:admin http://localhost:9080/alfresco/service/api/audit/contol

Below output is shown, as expected
{
"enabled" : true,
"applications":
[

{ "name": "Alfresco Tagging Service", "path" : "/tagging", "enabled" : true }

,

{ "name": "alfresco-access", "path" : "/alfresco-access", "enabled" : true }

]
}

6. Now logout from Alfresco Explorer
7. List the audit entries using the following command

curl -u admin:admin http://localhost:9080/alfresco/service/api/audit/query/alfresco-access?verbose=true

Output is similar to the following
{
"count":2,
"entries":
[
{
"id":1,
"application":"alfresco-access",
"user":"admin",
"time":"2012-08-29T18:40:14.994+05:30",
"values":

{ "\/alfresco-access\/logout\/user":"admin" }

},
{
"id":2,
"application":"alfresco-access",
"user":"guest",
"time":"2012-08-29T18:49:12.719+05:30",
"values":

{ "\/alfresco-access\/logout\/user":"guest" }

}
]
}

Expected Result: The user login events must also be returned but they one can only see logout events

I have tried the exact same steps on the trial version of Alfresco Enterprise 4.0.2.9 and observed the same behaviour as above.