PusherChat-iPhone install fail

installation failed

Aristotle:PusherChat-iPhone eric$ git submodule update --init --recursive
Cloning into Demo/SSToolkit...
remote: Counting objects: 5512, done.
remote: Compressing objects: 100% (1537/1537), done.
remote: Total 5512 (delta 3820), reused 5362 (delta 3694)
Receiving objects: 100% (5512/5512), 2.87 MiB | 82 KiB/s, done.
Resolving deltas: 100% (3820/3820), done.
Submodule path 'Demo/SSToolkit': checked out '6191e1be1ac06faacdd7ac36918242b271d2cdf7'
Cloning into External/libPusher...
remote: Counting objects: 2085, done.
remote: Compressing objects: 100% (787/787), done.
remote: Total 2085 (delta 1263), reused 2006 (delta 1202)
Receiving objects: 100% (2085/2085), 1.20 MiB | 72 KiB/s, done.
Resolving deltas: 100% (1263/1263), done.
Submodule path 'External/libPusher': checked out '4c68c15302233b2924aba2f31f120cb262250ccb'
Submodule 'Vendor/Mocky' (git@github.com:lukeredpath/LRMocky.git) registered for path 'Vendor/Mocky'
Submodule 'Vendor/TouchJSON' (https://github.com/TouchCode/TouchJSON.git) registered for path 'Vendor/TouchJSON'
Submodule 'Vendor/Zimt' (git://github.com/lukeredpath/zimt.git) registered for path 'Vendor/Zimt'
Cloning into Vendor/Mocky...
The authenticity of host 'github.com (207.97.227.239)' can't be established.
RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'github.com,207.97.227.239' (RSA) to the list of known hosts.
Permission denied (publickey).
fatal: The remote end hung up unexpectedly
Clone of 'git@github.com:lukeredpath/LRMocky.git' into submodule path 'Vendor/Mocky' failed
Failed to recurse into submodule path 'External/libPusher'

I have the same problem, any solutions???