I have a problem with my 8.9 tab, 3G version, ICS installed. I don't know why I cannot make video call on both Viber and Yahoo messenger.

Is there anybody know what's wrong with my Tab? Do I need to install something else? I think video call is the basic for any tabs so I really need to find out what's the reason?....

I spent already some days, reading a lot of comments from many forum, tried to install some Android versions...but nothing for me

Thank you so much for your help!