mod_groups don't add the contacts of virtual groups to users

[Θεόδωρος Γκουλιούμης]

              

I use the prosody server in my school so that teachers can communicate with students and students also with each other. Ι created virtual groups with childrens from each class in sharedgroups.txt file.I used mod _groups but contacts from each groups cannot be seen from students. I have to do something else for it to work?

I would appreciate any ideas...