Google Galaxy Nexus — Google assistant does not recognize me saying ok Google

I always had trouble with Galaxy assistant I never got the answer I wanted and the only action I could complete most the time was answer the phone, so when today my phone told me Google assistant is here I was full of hope that this would finally get me the same level of voice control I see Siri giving my Girlfriend on her phone. long story short while the assistant says it wants to learn my voice I have said ok google may be 100 times and it does not recognize it. So it most likely does not learn it has a fixed Idea what it wants to hear and unless I can learn this the assistant will not help me. What can I do to make Google recognize my voice as well as my accent. there is no point of me trying to vary the way I say ok Google as if it does not come natural it will always be frustrating. anybody has an idea as google just explains to me how to set it up which I clearly failed at.
Thanks for all your help