Then you must have broken it. Does it work if you remove this line?
Code:
#define USE_COLORCHAT
If not, start by checking if it's running.
Add debug after it in plugins.ini, does it print any messages in server console?
Add debug messages in form of "server_print()" or "client_print()" to see if where it halts and to check data that might be wrong.
EDIT: Sorry, I see the error now. You are using the names from chatcolor.inc but the parameters are from colorchat.inc. Just change all "client_print_color" to "ColorChat" and it should be fine.
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