I had chickenpox as a child but when tested i was told i am still not immune and can get it again. why did i not become immune like everyone else?

Immunity can fade: For most immunity is permanent in the majority of people given varicella (chickenpox) vaccine. There are exceptions and immunity can fade even in healthy people. Vaccine should be re-administered if you do not show evidence of immunity (two doses of vaccine separated by at least 4 weeks). Unlikely immune deficiency if otherwise well. Recheck titers 4-8 weeks post-vaccination to gauge response.

Hard to say: There are many blister producing viruses other than chickenpox and many kids are/were mistakenly labeled as CPX when they really had something else (HFM enterovirus ).Many health professionals never wanted these kids in their offices where they would expose others, so the label was applied as a guess by moms. Your antibody test may also not be a true reflection of your immune sate.