Whats app send text messages can not send Images

Hello all experts .......
I have a strange problem with whats app.
on my mobile i can send text messages to my contacts but can not send Picture or Voice Messages. i can receive pics and audios from others.
What may be the problem.
I have un installed and re-installed whtats app. formated the phone but no way.
any help would be appriciated.

thanks in advance.