I had a full std screening and i have a question?

I had a cervix swab and blood drawn i was tested for chlamydia, gonorrhoeae, RPR, hepatitis b and c, and HIV all came back negitive but the RPR came back nonreactive what does that mean? Also they said all the test were done using Ortho ECI is that pretty accurate in detecting HIV? All my results were sent to a hospital to get read then the results were sent to my doctors. Any details or more info would be appreciated.