Not sure if this has happened to you all

I went into Michaels on Sunday and tried to use a 40% coupon. I was told that I could not use it because the item I was trying to buy was on 20% off for the week. I asked them to charge full price and then apply the 40% and they told me no

The cashier said that they sometimes put most Halloween items on sale (around 20%) so that people don't use the 40 and 50% off coupons.
Anyways, printing and going to the other Michaels to try my luck