How long does a caution stay on your file?

My sister is currently doing social work at college and is trying to apply for a job within the health care sector. She has just been offered a job on the condition that her CRB check comes back clean. When she 11, she got caught stealing sweets in a shop, they cautioned her and that was that. She is now 21, and it is still on her record, and this is effecting her getting work, as she is being turned down due to the CRB checks coming back. As she was a minor at the time, surely this should be wiped from her record now? If not, Can this be appealed and how do I go about this?