A coupon code is rejected for a few predictable reasons. Check these before you give up on a deal.
Common reasons a code fails
The offer may be for new customers only, the code may need a minimum order, it may apply to one plan or product only, or it may have expired. Some codes also cannot be combined with an existing sale price.
What to do
Read the terms on the offer page, enter the code exactly as shown, and try the deal link without a code if the store already shows a discount at checkout.