Unsupported protocol during import_keys

[igalbk]

Here is the error that I get:
C:/app/Ruby22-x64/lib/ruby/gems/2.2.0/gems/gpgme-2.0.10/lib/gpgme/ctx.rb:385:in `import_keys': Unsupported protocol (GPGME::Error)
The code I used:

require 'rubygems'
require 'gpgme'
def passfunc(obj, uid_hint, passphrase_info, prev_was_bad, fd)
io = IO.for_fd(fd, 'w')
io.puts "hello"
io.flush
end
encrypted_data = GPGME::Data.new(File.open("C:/app/pgp/src/test/encryptedText.txt"))
key = GPGME::Data.new(File.open("C:/app/pgp/src/test/privateKey.skr"))
ctx = GPGME::Ctx.new :passphrase_callback => method(:passfunc)
ctx.import_keys key
decrypted = ctx.decrypt encrypted_data
decrypted.seek(0)
puts decrypted.read

This code works fine on mac but as mention throwing an error on windows (win7x64 and also Win 10), GnuPg for windows is installed and the %PATH% is configured.

I tried to set this
GPGME::Engine.set_info(GPGME::PROTOCOL_OpenPGP, nil, nil)
But then the error is:
C:/app/Ruby22-x64/lib/ruby/gems/2.2.0/gems/gpgme-2.0.10/lib/gpgme/engine.rb:60:in `set_info': Invalid crypto engine (GPGME::Error::InvalidEngine)
What is the problem?
Thanks!