Hi there, before we can help you - we need some more information!
Can you please post the errors you are recieving from Codeworks and Unreal when trying to package? The unreal log file would also be super helpful!
In regards to 4.11, I don’t believe 4.11 had support for Visual Studio 2015. Can you trying removing Visual Studio 2015 and installing Visual Studio 2013 to see if this combats your issue?
Thanks!