probably because nobody else is experiencing this problem, and so nobody has shrink-wrapped solutions or the ability to emulate your problem in order to diagnose it.

When you try the echo test, I assume it shows up as online (green indicator)? Does it do so on both wifi and cellular connections? Do your skype contacts definitely never show up online on either cell or wifi connections?

What country are you in? Who is your home broadband provider/mobile operator?

Have you tried deleting and recreating your skype account on the phone?

Create a dummy skype account and log into that on a laptop in your home wifi network. Then go online on your own skype account on the phone - can you see the dummy account as online?

"i cannot see the oline status at all of my skype contacts and also the possibiliti to make a video call" - does that mean that your skype contacts status shows offline but you can in fact skype them with an audio call, but just not a video call?