what is wrong with how I am trying to set opacity?

what is wrong with how I am trying to set opacity?

The disabled property gets set correctly, but opacity doesn't change. I call the function like this:
disables(true,'0.2');
  1. function disables(parm1,parm2) {
      var debug = 0;
      if (debug==1)
        alert('disables called with ' + parm1 + ',' + parm2);


      $("#divSearch :input").prop("disabled", parm1);
      $("#divSearch :input").css('opacity',parm2); 
     
      return true;  
    }