I heard there are certain diseases that cause false-negative hiv test results?

The CDC says a false negative result after 6 months is less than 1 percent, but how do you know you don't have one of these diseases that cause you to have a false-negative?I heard there are certain diseases that cause false-negative hiv test results?
In order to have an accurate result as far as hiv testing; you need to test yourself up to one year without any sexual contact from that individual. Any result in between has a probability to be a false negative.