Not compatible with the argument list

I am creating a slider puzzle game and I have come across an error and I have no idea what it means. It is the only error I have within my code and once I correct it my game should finally get to work. Thanks for your help in advance.

The error message I get is below:

Assets/puzzle.js(6,31): BCE0017: The best overload for the method 'UnityEngine.Vector3.Distance(UnityEngine.Vector3, UnityEngine.Vector3)' is not compatible with the argument list '(System.Object)'.

This is the code I am working with:

 var emptySlot : Transform;
 var xtemp;
 var ytemp;
 
 function OnMouseUp() {
       if (Vector3.Distance(transform.position.emptySlot.position)==1)
      {
          xtemp = transform.position.x;
          ytemp = transform.position.y;
          transform.position.x=emptySlot.position.x;
          transform.position.y=emptySlot.position.y;
          emptySlot.position.x=xtemp;
          emptySlot.position.y=ytemp;
          }
 }