Try to add in plugin_init :
PHP Code:
set_msg_block(gTeamScore, BLOCK_SET)
Also, you have to understand that "TeamScore" message is just used to set the visual part of score on client hud, if you want to change the real value, you need to set some internal data that can only be accessed with orpheu module.
Code i gave you will block messages that the game is sending, so only messages from the plugin gonna be received by players, it should be fine.
__________________