Why does my script gives an Error "Operator '*' cannot be used with a left hand side of type 'Object' and a right hand side of type 'float'." testing on Android?

 function DoRoll (aPoint, aAxis, aAngle, aDuration) {    
   
  var tSteps = Mathf.Ceil(aDuration * 30.0);  
  var tAngle = aAngle / tSteps;  
  var pos : Vector3; // declare variable to fix the y position  
    
 // Rotate the cube by the point, axis and angle  
   for (var i = 1; i <= tSteps; i++)   
   {   
     transform.RotateAround (aPoint, aAxis, tAngle);  
     yield WaitForSeconds(0.0033333);  
   }   
    
 // move the targetpoint to the center of the cube   
    transform.Find("targetpoint").position = transform.position;  
   
 // Make sure the y position is correct   
    pos = transform.position;  
    pos.y = startY;  
    transform.position = pos;  
       
 // Make sure the angles are snaping to 90 degrees.       
    var vec = transform.eulerAngles;  
    vec.x = Mathf.Round(vec.x / 90) * 90;  
    vec.y = Mathf.Round(vec.y / 90) * 90;  
    vec.z = Mathf.Round(vec.z / 90) * 90;  
    transform.eulerAngles = vec;  
       
 // The cube is stoped  
    ismoving = false;       
 }

How to fix this error? Is it possible? Oh, and an Error is in line 3 (place where is written "var tSteps = ...")