Problem of getting visa of Indonesia

I am Student and i am going to give CCIE-SP Lab Exam in jakarta (Indonesia).My exam date is 5th May 2015 and i am going to jakarta on 30th April but i am facing problem of getting visa of Indonesia.Embacy required Visa Invitation letter issued by indonesia But i have no sponser ...
I have issued invitation letter from America in which is it mention that i am going to give lab exam in jakarta but embacy required invitation letter from jakarta ..
Any body help me i am very thankfull to you

Yes.
Get a letter from whoever you're taking the exam with.
That's the only legal way.

You should ask the institution in Jakarta, where you are going to make your exam, to provide the invitation/sponsor letter for the visa.

Better rush because it will take quite some time to get a visa approval