Hi Paul,
Please make sure that your document type, meaning the file extension, is included in the configuration option "File Extensions for Viewing".
Also, please check the configuration option "Show View Button" under the Themes tab to make sure it is enabled.
If you have checked the configuration and are sure that everything is set correctly, then please submit a ticket under the EDocman category through the Support Tickets menu at the top of our website, and provide your site information together with an administrator account. I will then check the issue with the View button display for you.
Best regards,
Dam