Is there a message to you that you need Admin rights?
Find the Sentinel program in your Start menu (on mine it is listed under Uniden), right click on it, and select Run As Administrator. Or if you are trying to install the program you can do the same procedure on the install file to Run As Administrator. Some programs are just coded to require that.
If you have your User Account Control setting to high, that can prevent doing things that require Admin rights. If you have it set too high, you will need to lower the setting and Restart the PC BEFORE doing the install. You can raise the UAC back up if you want too. Normally I recommend the second from the highest setting for an Administrator.