Devices will try once and if failed will not try again.
If you want them to try again you need to set the task to be repeating with the retry only devices that did not succeed.
MarXtar Ltd/MarXtar Corporation
LANDESK One Development Partner
The One-Stop Shop for LANDESK Enhancements
To add to MarXtar reply, another option, if you want the clients to try until they get the install, is to set the task as either a "policy-supported push" or just "policy" and make it required. This will ensure that all clients will attempt the install when they come online