I've been having the same problem the past week how do I get it to work
@Lisatay187 @jmg55 Welcome to the community. There have been some similar reports and NOW TV are looking into the cause. In the meantime have you tried opening the ITV Hub from the My Apps screen and then searching for and watching the programme you want once the app is open.
That might work for you rather than clicking anything on the homescreen or the Catch-Up screen.
Also if you could post the serial number of your box (found on the bottom) into this thread it would help NOW TV investigate
@Nessaa Welcome to the community. Until NOW TV and ITV work out the issue, you should be able to watch by going to the My Apps screen of the NOW TV box/stick and opening ITV Hub from there. You'll have to search/browse for the programme you want to watch manually.