Before every session you should do the set up and test process to ensure that PowerPoint can see the receiver.
You must also clear any previous voting data from the presentation. Voting will not open if there is data present. Instead the result of the previous vote will be shown.
You should check the CLiKAPAD menu and ensue that Auto launch votes is on. If it is not, you should turn it on if you want the voting to open automatically. Otherwise you will need to press V on each voting slide in order to launch the vote.
It is possible that the version of the voting software you have will lose compatibility with your more up to date versions of Windows and PowerPoint. Check that you are runnning the most up to date version.