I have purchased a KA7178, hoping it will work with my KN series KVM, but it seems to be uncooperative. What can I do? 

If the KA7178 you purchased is an old hardware version (HW. A0), it will not work with KN series KVMs. Please contact your local sellers, wholesale sellers, or distributors for product exchange for a newer hardware version. 
To determine the current  hardware version, refer to the picture below