AddRecord adding wrong data

Im trying to create a button that adds a line to an inventory table if an item is unable to be returned. My code is adding a line to the inventory table but not the correct information. It needs to copy the line item information.
Here is the info it is supposed to be copying:
ProductCode = 20
Product - Supplier = Interceramic

But it is inserting:
ProductCode = 1
   (It is inserting the 20th item in the Products List)

Here is my code:
var text URL = URLRoot() & "db/" & [_DBID_SHOWROOM_INVENTORY_LEVEL] & "?a=API_AddRecord"
& "&_fid_7=2"
& "&_fid_6=Unrecoverable"
& "&_fid_12=" & URLEncode([ProductCode]);

"javascript:" &
"$.get('" & 
$url & 
"',function(){" &
"location.reload();"&
"});" &
"void(0);