Hi Momoko19,
Welcome to the community forum and thanks for posting.
PayPal balance is the result of the payments received through PayPal, therefore the amount shown in your account balance does not coincide with your credit or debit card availability. The most common reason for a negative balance is that a payment made from your bank failed but there may be other reasons. As your question is very account specific, I would suggest contacting us via Facebook - https://www.facebook.com/PayPal/, Twitter - @AskPayPal, email or phone and we would be happy to advise.
-Intars
