Thank-you for contacting Slingbox Forum.
I am sorry you are having problems when connecting to the Slingbox!
It may be that you would want to go through the set-up for Internet Viewing at setup.slingbox.com on the home computer just to be sure it understanding it can connect without the home computer being powered on. Another option will be to uninstall the App and reinstall the App from the purchased App location on your phone.
Here is a link to assist you:
Hope this helps with your issue.
Have a great day!
Sling Moderation Team