unable to find datablock?

I've implemented the ability to throw my weapon when it is fired using this Throwing code snippit.

I can pickup the item, throw it, but when I pick it up again, I get this in the console:
Unable to find object: '1418' attempting to call function 'getDataBlock'

It picks it up fine, it's just writing that line in the console which I want to stop. I'm sure I can just put a return on the function where it's having the problem, but I would like to know why there isn't a datablock associated with it.

Where it runs into the problem calling getDataBlock():

function Armor::onCollision(%this,%obj,%col,%vec,%speed)
{
   if (%obj.getState() $= "Dead")
      return;
   // Try and pickup all items
   if (%col.getClassName() $= "Item")
      %obj.pickup(%col);

   // Mount vehicles
   %this = %col.getDataBlock();

This is the code that creates the object (%data is the name of my datablock):

function ShapeBase::throwItem(%this, %data)
{
   // Construct item to throw from the given datablock
   // (with a random rotation around the z axis)
   %item = new Item() {
      dataBlock = %data;
      rotation = "0 0 1 " @ (getRandom() * 360);
   };

   // Make sure the object will be deleted when the
   // mission ends.
   MissionCleanup.add(%item);

   // Call the workhorse throw method...
   %this.throwObject(%item);
}

Now, as far as I can tell, I'm creating a datablock, because I can see the object that I'm throwing. So why am I getting this error?

I'm stumped as to how to go about fixing or debugging it.