Sunburn even when drenched in sunscreen?

I have a light skin tone because I never have been able to tan I just burn. My mom drenched me in sunscreen she put me in 30 and another sunscreen that makes it to were u can stay in the sun 8times longer than usual without sunburning. I get back to the condo and im BURNT BAD! Im wondering are some people prone to sunburn even with sunscreen?