Question Regarding HIV Testing

I have done lots more research in internet and I have got one queston regarding Antibody test. I have read some article saying that If person progressed to AIDS,  some time the antibody test does shows false negative as there vanishing some types of HIV antibodies. Assume If a person is testing this antibody test after two years of exposure, what are the possibilities for false Negative result(Other than Laborotry mistakes). Should he need to undergo multiple tests to conclude the result. Also is PCR test is efficient test among all HIV test as it picks the Virus directly rather than HIV Antibodies? Pls give your thoughts on this.

[Teak]

Once someone has AIDS they will be under treatment and they aren't given antibody tests. ZERO for a false negative test after two years being infected. PCR tests are not approved for diagnosing HIV.

[crazythoughts34]

Is it possible antibodies goes below detectable level after some peroid of infection?. In healthy people the antibodies produced always?

[Teak]

Not without the help of medication.