I am a permanent resident of the United States since July 2011. At the moment I am visiting my family in my country and working on some paperwork here. I am in a process of receiving a permit to leave my land( a stamp into my passport).
Migration Police office requires one last document that is left in order to give me this permit. It is the invitation from the US embassy that states that I am allowed by the US government to become a resident ( even though I am already one). I have presented my US residency card to the migration police officer, but they still want me to bring this invitation from the US embassy.
How do I proceed?Where could I receive such a paper?

Best regards,