First, check the following.
Are all of the connections correct?
Were the instructions in the manual followed correctly?
Is the connected device being operated correctly?
If the earphones do not operate properly, check the corresponding issue here.
If the issue is not covered here, there may be a malfunction. Contact the store where you purchased the earphones. If the staff at the store where you purchased the earphones also do not know how to resolve the issue, contact the Denon Customer Service Center or your nearest Repairs Center.