So what is wrong here?

I've tested and when I hit enemy with grenade screen goes very weird
PHP Code:
#define DMG_HEGRENADE (1<<24)
new g_hegrenade_rank[33];
PHP Code:
RegisterHam(Ham_TakeDamage, "player", "Fwd_PlayerDamaged")
PHP Code:
public Fwd_PlayerDamaged(id, inflictor, attacker, damage, damagebits)
{
if ( !(1 <= attacker <= g_iMaxPlayers) )
return HAM_IGNORED;
if( damagebits & DMG_HEGRENADE && id != attacker && g_hegrenade_rank[attacker] == 1)
{
SetHamParamFloat(4, damage * 3.0);
return HAM_HANDLED;
}
return HAM_IGNORED;
}