Object of type class java.lang.Boolean cannot be used as an array Error

I have a very frustrating problem with this cfc, it works as it is designed when updating a quantity when it is greater than 0 but the seccond that the quantity is set to zero i get the "Object of type class java.lang.Boolean cannot be used as an array".  what is really interesting is that it happens on two diffrent lines.  -- MARKED AS SUCH --

it seems as though the problem only occurs where the code loops thru the array, perhaps i've set some variable wrong, but even then it shouldnt work for any quantity.  

Thank you for any help in advance.  


<CFCOMPONENT>
  <!--- Initialize the cart's contents --->
  <!--- Because this is outside of any <CFFUNCTION> tag, --->
  <!--- it only occurs when the CFC is first created --->
  <CFSET This.CartArray = ArrayNew(1)>


  <!--- *** ADD Method *** --->
  <CFFUNCTION
    NAME="Add"
    HINT="Adds an item to the shopping cart">
    <!--- Two Arguments: ProductID and Quantity --->
    <CFARGUMENT NAME="ProductID" TYPE="numeric" REQUIRED="Yes">
    <CFARGUMENT NAME="Quantity" TYPE="numeric" REQUIRED="No" DEFAULT="1">

    <!--- Get structure that represents this item in cart, --->
    <!--- then set its quantity to the specified quantity --->
    <CFSET CartItem = GetCartItem(ProductID)>
    <CFSET CartItem.Quantity = CartItem.Quantity + Arguments.Quantity>
  </CFFUNCTION>  
 
 
  <!--- *** UPDATE Method *** --->
  <CFFUNCTION
    NAME="Update"
    HINT="Updates an item's quantity in the shopping cart">
    <!--- Two Arguments: ProductID and Quantity --->
    <CFARGUMENT NAME="ProductID" TYPE="numeric" REQUIRED="Yes">
    <CFARGUMENT NAME="Quantity" TYPE="numeric" REQUIRED="Yes">

    <!--- If the new quantity is greater than zero --->  
    <CFIF Quantity GT 0>
       <!--- Get structure that represents this item in cart, --->
       <!--- then set its quantity to the specified quantity --->
      <CFSET CartItem = GetCartItem(ProductID)>
      <CFSET CartItem.Quantity = Arguments.Quantity>
      <!--- If new quantity is zero, remove the item from cart --->
    <CFELSE>
      <CFSET This.Remove(ProductID)>
    </CFIF>
  </CFFUNCTION>  

 
  <!--- *** REMOVE Method *** --->
  <CFFUNCTION
    NAME="Remove"
    HINT="Removes an item from the shopping cart">
    <!--- One Argument: ProductID --->
    <CFARGUMENT NAME="ProductID" TYPE="numeric" REQUIRED="Yes">

    <!--- What position is this item occupying in the cart? --->
    <CFSET CartPos = GetCartPos(ProductID)>
   
    <!--- Assuming the item was found, remove it from cart --->
    <CFIF CartPos GT 0>
      <CFSET This.CartArray = ArrayDeleteAt(This.CartArray, CartPos)>
    </CFIF>
  </CFFUNCTION>  
 
 
  <!--- *** EMPTY Method *** --->
  <CFFUNCTION
    NAME="Empty"
    HINT="Removes all items from the shopping cart">
   
    <!--- Empty the cart by clearing the This.CartArray array --->
    <CFSET ArrayClear(This.CartArray)>
  </CFFUNCTION>
 

  <!--- *** LIST Method *** --->
  <CFFUNCTION
    NAME="List"
    HINT="Returns a query object containing all items in shopping cart.  The query object has three columns: ProductID, Quantity and Price."
    RETURNTYPE="query">

    <!--- Create a query, to return to calling process --->
    <CFSET q = QueryNew("ProductID,Quantity,Price,Name,Dosage,Count")>
   
    <!--- For each item in cart, add row to query --->
    <CFLOOP FROM="1" TO="#ArrayLen(This.CartArray)#" INDEX="i">      ------- FIRST ERROR HERE ------------
      <CFSET QueryAddRow(q)>
      <CFSET QuerySetCell(q, "ProductID",  This.CartArray[i].ProductID)>
      <CFSET QuerySetCell(q, "Quantity", This.CartArray[i].Quantity)>
        <CFSET QuerySetCell(q, "Price", This.CartArray[i].Price)>
        <CFSET QuerySetCell(q, "Name", This.CartArray[i].Name)>
        <CFSET QuerySetCell(q, "Dosage", This.CartArray[i].Dosage)>
        <CFSET QuerySetCell(q, "Count", This.CartArray[i].Count)>
    </CFLOOP>

    <!--- Return completed query --->    
    <CFRETURN q>    
  </CFFUNCTION>  


  <!--- Internal GetCartPos() Method --->
  <CFFUNCTION
    NAME="GetCartPos"
    RETURNTYPE="numeric"
    ACCESS="private">
    <!--- Argument: ProductID --->
    <CFARGUMENT NAME="ProductID" TYPE="numeric" REQUIRED="Yes">
   
    <!--- Get position, if any, of ProductID in cart query --->
    <CFSET CurrentArrayPos = 0>
    <CFLOOP FROM="1" TO="#ArrayLen(This.CartArray)#" INDEX="i">           ---------  SECCOND ERROR HERE ----------------
      <CFIF This.CartArray[i].ProductID EQ Arguments.ProductID>
        <CFSET CurrentArrayPos = i>
        <CFBREAK>
      </CFIF>
    </CFLOOP>    
   
    <!--- Return the position --->
    <CFRETURN CurrentArrayPos>
  </CFFUNCTION>  


  <!--- Internal GetCartItem() Method --->
  <CFFUNCTION
    NAME="GetCartItem"
    RETURNTYPE="struct"
    ACCESS="private">
    <!--- One Argument: ProductID --->
    <CFARGUMENT NAME="ProductID" TYPE="numeric" REQUIRED="Yes">
   
    <!--- Get the position of the item in This.CartArray --->
    <CFSET CartPos = GetCartPos(ProductID)>
   
    <!--- If item for this ProductID was found, we will return it --->
    <CFIF CartPos GT 0>
      <CFSET CartItem = This.CartArray[CartPos]>
    <!--- If item was not found, create new one and add to cart --->  
    <CFELSE>
        
        <cfquery name="Pricing" dataSource="Cart">
                    SELECT *
                  FROM DrugDetails
                  WHERE DetailID = #Arguments.ProductID#
        </cfquery>      
   
        <CFSET CartItem = StructNew()>
      <CFSET CartItem.ProductID = Arguments.ProductID>
      <CFSET CartItem.Quantity = 0>
        <CFSET CartItem.Price = '#Pricing.Price#'>
        <CFSET CartItem.Name = '#Pricing.Name#'>
        <CFSET CartItem.Dosage = '#Pricing.Dosage#'>
        <CFSET CartItem.Count = '#Pricing.Count#'>
      <CFSET ArrayAppend(This.CartArray, CartItem)>

      </CFIF>

    <!--- In either case, return the item --->
    <CFRETURN CartItem>
  </CFFUNCTION>  
 
</CFCOMPONENT>