How can I get my friends to approach .

Ill go out to the bar with them or in a social setting and do an approach in front of them or tell them what to say but when I try to get them to do a single approach it never works. I know they want to be able to approach and they even have someone in real life showing them how to do it but they still can't do it. Is there any way I can make it more likely for them to do an approach ?