It takes a while for the body to build up enough pregnancy hormones, hCG, to register on HPTs. A study was done recently that showed a higher rate of false negatives when an HPT was taken within 10dpo. It reduced slightly at 12dpo and significantly more at 14dpo. Therefore, its important to wait another week to test again to try avoiding another false negative. Another study by Consumer Reports showed EPT Early Response faired the best in accuracy. Take Sania's advice with using first morning urine, since hCG will be more concentrated. Good luck!
yes take one more hpt with your first morning urine.
you may have just tested early if you dont get your period in a week take another test :) best of luck