did you make sure to go into settings to enable it? go in there and check it off. prime is not a supported device but if you click video chat in settings, it will work. plus they just updated so it might work even better now.
Motorola Atrix-Rooted on froyo 2.2.2 (Retired)
IPAD- 32GB WiFi ver. 4.2.1
Transformer Prime 32GB(Retired)
NEXUS 7 16gb Unlocked & Rooted JB 4.2.2 Twrp. TEAM EOS4
Galaxy Note 10.1 32gb- Stock JB 4.1.2
Samsung Galaxy SIII - Phablet
Prime/Tegra3 Gamers Thread