If after installing the Magento Shiptheory extension, you find a blank screen when trying to access the Shiptheory Messages section of the Sales Menu in the Magento admin panel, as shown below, please follow the below steps.
1. Have you cleared your cache?
Make sure you have completed a full Flush Cache Storage from the System -> Cache Management menu in Magento.
2. Check the Shiptheory Extension(s) are not disabled
From the System -> Configuration menu, find the Advanced tab on the Advanced menu, as shown below.
You will now see a list of all the enabled extensions on your store. Browse down to any that start Shiptheory_.... There may be more than one. If they are disabled, as shown below, set them to Enabled and Save.
3. Still having trouble?
Please get in touch with support. If you provide us with your Magento admin url, username and password, we will be happy to investigate.