I've spent the past 7 hours trying to figure out why Office Web App Server will not work correctly with my Sharepoint Server (2013). When ever I try to open or edit a document via web app it keeps giving me the Sorry there was a problem and we can't open this document. I know the Office Web App Server was set up correctly, gave me the xml file and pluse I tied it into exhange and it works just dandy with it. I have unbounded the server four times and re bound it and made sure that I ran Set-SPWOPIZone command for external and https. I have added the domain to the Trusted list on the Wac Server. I have also made sure that the AllowOAuthOverHttp was false. I have no clue what to do any more it works with lync and exchange. I'm sure I'm not the only person who has ran into this problem lol.