you are not responding to the latest message - wrong email


Outlook version
Email Account
Using Office 2013 with Intermedia exchange server. When try and respond to and email the message comes up "you are not responding to the latest email in this conversation". Clicking that takes us to another email, but for a different person, subject, and email address. The only thing I see that relates at all is the for both emails. I tried a repair on the ost file. But it's still doing it. The Conversation View is not selected.
Any idea what I should look at?