Hi RobWaibelJr,
Try querying a ticket with a direct API call like
http://YourServerName:81/api.aspx?Action=GetTicket&Key=123456789&TicketID=1
If the same 500 error is occurring and assuming you've added an API key in the Configuration\Ticket API tab, the issue could be related to your web server setup.
It would be best to send a screenshot of the error message when making a direct call to support@lansweeper.com