Dollar Tree review: 10% off coupon was not honored

I presented my 10% of coupon, but nothing was taken off at the register. The store manager called her supervisor, but the supervisor did not answer. I was not the only one this happened to. The Dollar Tree Website did not allow me to complain. I have no problem with the employees. kist aggrevated that the website was useless. It was only $2.00, but the 10% coupon was the only reason I went today.