You need to have the proper include file for the functions that you want to use. Notice that the include that you're using is called "colorchat" but you're using a function called "chatcolor". Either get an include that contains "chatcolor" or use the functions defined in your include file.
Alternatively, if you're using AMX Mod X 1.9.x or newer, you'll have a built-in color chat function called
client_print_color() so you can just use that one instead and not need any extra include files.
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