Have you tried pressing the f7 or f4 key. Sometimes that will work. If not try pressing the FN or Function key.
Depending on what laptop you have (I am assuming it is a laptop), you have to press different keys. Another key that might work is f3.
You might even have to start with the f1 key and try all the keys till you get to f12. Different ones work for different devices.
okay give me a second.
Okay I am not sure about the logitech keyboard for Ipads. Will opt out so that another Expert can come on to help you.