Attempt to call field Create (nil value) - (SWEP) HELP!

[DJMullaney]

Hi, I'm trying to make a SWEP but I'm getting a lua error "Attempt to call field Create (nil value)"

 function SWEP:SecondaryAttack() 
	if ( !self:CanSecondaryAttack() ) then return end 
 
	local eyetrace = self.Owner:GetEyeTrace()
	self:EmitSound ( self.Secondary.Sound ) //Adds sound
	self:ShootEffects() 
	local explode = ents.Create("env_explosion") //THIS IS THE LINE THAT IS CAUSING THE ERROR!
		explode:SetPos( eyetrace.HitPos ) //Puts the explosion where you are aiming
		explode:SetOwner( self.Owner ) //Sets the owner of the explosion
		explode:Spawn()
		explode:SetKeyValue("iMagnitude","175") //Sets the magnitude of the explosion
		explode:Fire("Explode", 0, 0 ) //Tells the explode entity to explode
		explode:EmitSound("weapon_AWP.Single", 1000, 1000 ) //Adds sound to the explosion
 
	self:SetNextPrimaryFire( CurTime() + self.Secondary.Delay ) 
	self:SetNextSecondaryFire( CurTime() + self.Secondary.Delay ) 
	self:TakePrimaryAmmo(self.Secondary.TakeAmmo) 
end