Melee lua SWEP attack animation not always starting

[iKebab897]

I'm creating a gamemode with custom weapons.

But there's a problem with this melee weapon, the attack animation sometimes starts and sometimes doesn't.
Here's the code.

AddCSLuaFile()

SWEP.Base = "weapon_base"
SWEP.PrintName = "Hard Hitter"
SWEP.Category = "Stalkers"

SWEP.Author = "iKebab897"
SWEP.Purpose = "Stalk and kill your preys"
SWEP.Instructions = "LMB: Attack, RMB: Invisibility, RELOAD: Ability"

SWEP.Spawnable = false
SWEP.AdminOnly = false

SWEP.Slot = 0
SWEP.SlotPos = 0
SWEP.DrawAmmo = false
SWEP.DrawCrosshair = true

SWEP.UseHands = true
SWEP.ViewModelFlip = false
SWEP.ViewModelFOV = 60
SWEP.BobScale = 4.65
SWEP.SwayScale = 1.8
SWEP.ViewModel = "models/weapons/v_stunstick.mdl"
SWEP.WorldModel = "models/weapons/w_stunbaton.mdl"

SWEP.Primary.ClipSize = -1
SWEP.Primary.DefaultClip = -1
SWEP.Primary.Automatic = false
SWEP.Primary.Ammo = "none"
SWEP.Primary.Delay = 1.15

SWEP.Secondary.ClipSize = -1
SWEP.Secondary.DefaultClip = -1
SWEP.Secondary.Automatic = false
SWEP.Secondary.Ammo = "none"
SWEP.Secondary.Delay = 1.5

sound.Add( {
name = "antlionguard_growl_high",
channel = CHAN_AUTO,
volume = 1.0,
level = 55,
pitch = { 100, 110 },
sound = "npc/antlion_guard/growl_high.wav"
} )
sound.Add( {
name = "antlionguard_attack_double",
channel = CHAN_VOICE,
volume = 1.0,
level = 55,
pitch = { 100, 110 },
sound = "npc/antlion/attack_double1.wav"
} )

local HitSound = Sound( "Weapon_Crowbar.Melee_Hit" )
local HitWorldSound = Sound( "Weapon_Crowbar.Melee_HitWorld" )
local MissSound = Sound( "Weapon_Crowbar.Single" )

function SWEP:Initialize()
if self.Owner:IsValid() then
self:SetHoldType( "melee" )
end
end

function SWEP:PrimaryAttack()
if self.Owner:GetNWBool( "inv", false ) == false then
self:SetNextPrimaryFire( CurTime() + self.Primary.Delay )

if ( CLIENT ) then return end

local tracedata = {}

tracedata.start = self.Owner:GetShootPos()
tracedata.endpos = self.Owner:GetShootPos() + self.Owner:GetAimVector() * 75
tracedata.filter = self.Owner
tracedata.mins = Vector( -15 , -15 , -15 )
tracedata.maxs = Vector( 15 , 15 , 15 )

if ( self.Owner:IsPlayer() ) then
self.Owner:LagCompensation( true )
end

local tr = util.TraceHull( tracedata )
local vm = self.Owner:GetViewModel()
local pitch = math.random( -40, 40 )
local yaw = math.random( -40, 40 )
local roll = math.random( -40, 40 )

if self.Owner:IsOnGround() then
self.Owner:SetWalkSpeed( 1000 )
self.Owner:SetRunSpeed( 1200 )
timer.Simple( 0.01, function()
self.Owner:SetWalkSpeed( 185 )
self.Owner:SetRunSpeed( 415 )
end )
end

timer.Simple( 0.055, function()
if tr.Hit then
self:SendWeaponAnim( ACT_VM_HITCENTER )
self.Owner:SetAnimation( PLAYER_ATTACK1 )
if tr.Entity:IsPlayer() or tr.Entity:IsNPC() or tr.Entity:Health() > 0 then
self.Owner:EmitSound( HitSound )
self.Owner:SetWalkSpeed( 15 )
self.Owner:SetRunSpeed( 15 )
tr.Entity:TakeDamage( tr.Entity:GetMaxHealth() / 7 + math.random( 20, 28 ), self.Owner, stalk )
net.Start( "SmallStun" )
net.Send( self.Owner )
else
self.Owner:ViewPunch( Angle( pitch, yaw, roll ) )
self.Owner:EmitSound( HitWorldSound )
self:SetNextPrimaryFire( CurTime() + self.Primary.Delay + 0.55 )
self.Owner:SetWalkSpeed( 65 )
self.Owner:SetRunSpeed( 65 )
net.Start( "HardStun" )
net.Send( self.Owner )
self.Owner:SetVelocity( self.Owner:GetForward() * -750 + Vector( 0, 0, -300 ) )
end
else 
self:SetNextPrimaryFire( CurTime() + self.Primary.Delay + 0.1 )
self:SendWeaponAnim( ACT_VM_MISSCENTER )
self.Owner:EmitSound( MissSound )
self.Owner:SetWalkSpeed( 45 )
self.Owner:SetRunSpeed( 45 )
net.Start( "MediumStun" )
net.Send( self.Owner )
end
end )
if ( self.Owner:IsPlayer() ) then
self.Owner:LagCompensation( false )
end
end
end

function SWEP:SecondaryAttack()
self:SetNextSecondaryFire( CurTime() + self.Secondary.Delay )

if ( CLIENT ) then return end

net.Start( "ChangeInv" )
net.Send( self.Owner )

net.Start( "SecondarySound" )
net.Send( self.Owner )
end