Missing Video And Sound

Hello everyone,

I am new to this software and I wanted to use it to make video calls to m family back in my home country. The family I use it with are older people in their 60s and early 70s but they are quite used to technology and are not 'technophobes'.

We tried to use it last week, however, when things were set up and running, they could see me but could not hear me and I could hear them but could not see them. We tried for such a long time to see if we could solve the problem but in the end we had to turn it off and just make a normal phone call.

Is there a solution to this problem? 

Thank you in advance for your help.