Enzyme-linked immunoassay (ELISA) or enzyme immunoassay (EIA): The ELISA (also referred to as EIA) detects antibodies against recombinant HCV antigens. "First generation" ELISAs used a single antigen; later tests added additional antigens.146-148 Second and third-generation tests are both in standard use. Because of concerns about false-positive tests, particularly in low-prevalence populations (such as blood donors or asymptomatic adults), the CDC has recommended confirming positive ELISA results with a supplemental test (recombinant immunoblot assay or polymerase chain reaction), unless the signal-to-cut-off ratio is above a predetermined threshold that has been shown to confirm positive more than 95% of the time.90
Your test result indicates it is unlikely anyone can predict you are HCV + I would follow the advisement on the what is written on your test result ("if further clarification is required suggest Hep C RNA PCR qualitative/quantitative assay to confirm presence of virus/viral load") or NAT for HCV RNA
http://www.medhelp.org/user_photos/show/322190?personal_page_id=414409
Plus the conclusion in this study kind of explains it:
The HCV-RIBA indeterminate status may indicate either a non-specific reaction (false positive) or a real pre-existing or initial infection and does not, therefore, enable a prediction of outcome.
The use of HCV genomic assays (nucleic acid amplification testing), which are more specific than antibody-based assays (ELISA, RIBA), therefore improves HCV blood donor testing by allowing an accurate interpretation of such primary assays.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2626846/