That's probably because gmsgFade is never set to anything. Just creating the variable will automatically initialize it to 0. You need to get the message ID of the fade message before you can use it. So what you need to do is put something like this in plugin_init like this:
Code:
public plugin_init() {
gmsgFade = get_user_msgid("ScreenFade")
}
or you could also get rid of gmsgFade variable and make the message_begin like this:
Code:
message_begin(MSG_ONE, get_user_msgid("ScreenFade"), {0,0,0}, player)
Either way should work, but I don't know if that variable gmsgFade is used elsewhere within your plugin or not.