My guess is that there is something wrong with the format of the supplied LogonTrigger.UserId property value. The following is information from the Microsoft support page:
The identifier of the user. For example, "MyDomain\MyName" or for a local account, "Administrator".
This property can be in one of the following formats:
• User name or SID: The task is started when the user logs on to the computer.
• Group name or SID string: The task is started when a member of the user group logs on to the computer.
• NULL: The task is started when any user logs on to the computer.