can't install Viber : set up : invalid phone number ?

Hi, i had viber installed to my iphone 3GS (4.3.5) - everything working fine untill i decided to install Viber on my mini ipad.

After asking my phone number on ipad, my iphone went on & on asking me to connect with my adress book, to give my phone number again, sending me a code and so on ! Big mess betwin iphone & ipad. Well i decided to delete the viber on ipad and when i lauched viber on my iphone again, it was back to set up as if i was just installing it for the first time !

So i was willing to re-install it. But after answering about the country and "ok" to connect to my adress book. The following step is to give the phone number (without the 0, directly 6), and the answers was "unvalid number" (in french : numero non valide) ! So failure…

What should i do ?

I've tried to delete viber, reboot the iphone, connect it to my mac, download viber again… still the same problem ! UNVALID NUMBER ! and of course this phonenumber is valid. Anybody knows how to solve this ?

Thanks a lot for your help,

K