I work for Coby technical support
. Our customer service phone number is 1-800-727-3592.
Traditionally, universal remotes do not work with COBY dvd players. The fact that you've found one that works at all is surprising. There isn't a true solution to your problem, however, because Philips created the coding for that remote without any input from COBY. The only thing you can try is a different COBY code if there is one in the code section of the book that came with your Philips remote.
While this solution doesn't "fix" your problem, I hope that by giving you the facts, I've enabled you to make an informed decision as to what to do next.
Please let me know if I can assist you further.