Many of our newer titles are currently only available for our apps running version 5.9 and above.
Olive Tree has transitioned to a new file format for our resources. This change will allow us to continue offering great resources in the future as well as new types of resources, such as interlinear Bibles and support for more languages. This change in technology also opens the door for resources like dynamic timelines, flash cards/memorization aids, and multi-media resources.
To see whether a resource is available for your app, please look at the product page for the resource on OliveTree.com. You'll see the image below: