admin api - correct url syntax to getUsers for an event instance.

I'm trying to use the admin api to call the function getUsers() and I'm not sure of the correct URL syntax. I want to return the number of users currently connected to an event instance. Could someone provide an example of what the URL connection string would look like?

I tried the following syntax

http://localhost:1111/admin/getUsers?auser=USER&apswd=PASSWORD&appInst=livepkgr/_definst_/myEvent

but it returns this error message.

<?xml version="1.0" encoding="UTF-8"?>

-<result>

<level>error</level>

<code>NetConnection.Admin.CommandFailed</code>

<timestamp>10/26/2012 8:06:23 AM</timestamp>

</result>

>>>>>>>>>>>>>>>>>>>>>>>>

I can successfully use the ping command: http://localhost:1111/admin/ping?auser=USER&apswd=PASSWORD

<?xml version="1.0" encoding="UTF-8"?>

-<result>

<level>status</level>

<code>NetConnection.Call.Success</code>

<timestamp>10/26/2012 8:12:51 AM</timestamp>

</result>

In my FMS.ini file I do have  USERS.HTTPCOMMAND_ALLOW = true

In my USERS.xml file I have

<HTTPCommands>

            <Enable>${USERS.HTTPCOMMAND_ALLOW}</Enable>

            <Allow>ping,getUsers,getUserStats,getServerStats</Allow>

            <Deny></Deny>

            <Order>Deny,Allow</Order>

</HTTPCommands>

Thanks!