[FreshKilla]

pawn Код:

public OnPlayerPickUpPickup(playerid, pickupid)
{
    switch(pickupid)
    {
        case ballasarmor:
        {
            if(gTeam[playerid] == TEAM_BALLAS) GivePlayerArmour(playerid,100);
            else SendClientMessage(playerid, COLOR_SAND, ":SERVER: This Armor belongs to Ballas Team !");
        }
    }
    return 1;
}

Also you might want to check if your gTeam's are assigned correctly.