Ticket Response Report

We created a ticket response report, but it is not working as we expected. We want to know how long it takes from the time a ticket is created to the time of the first response to the ticket. We set up the report using "Create to Initial Respond (Op)" and "Initial Responded Date." We assumed that "Initial Responded Date" is the date that a technician first responded to the requestor in the ticket by updating or commenting on the ticket and notifying the requestor.  However, when we started examining the data, it does not always seem to capture what we understand as the first response to the ticket. Please see the attached document for an example. Can you explain what we did wrong?  Thanks!