Viber v2.2.2 update required

Please , I have a problem with my viber version as I have downloaded from app stores V2.2.0 and the new release one in anroid market V2.2.2.22 and when I am trying to call my brother it is not working as he have Samsung mobile with the latest version from android market and when he is trying to call me he have on notification that my viber version is older than him and I shall update my version to be able to speak with him. Please send to me the update link or tell me how to update my viber version to the latest version release in the Android market. thanks. please reply ASAP.