function validate_form(thisform)
{
  var feedback = document.getElementById('jsFeedback');
  plate = thisform.regLookUp.value; 
  originalPlate = plate;

  if(thisform.regLookUp.value == ''){
     feedbackString = "Please enter your bike<br />registration number.";
     //type = 'invalid';
  }
  else{ 

     var type;
     regEx = / /g;
     plate = plate.replace(regEx, "");

     if(plate.match(/^[A-Za-z0-9]+$/)) {
         type = 'acceptable';
   
     }
     else{
           feedbackString = "Sorry, your bike registration '<span id=\"originalPlate\">"+originalPlate;
           feedbackString += "</span>' doesn't seem to be valid.";
           type = "invalid";
     }
   
  }


  if(type=="invalid"){
     feedback.innerHTML = feedbackString;
     feedback.style.display="block"
     return false; 
  }
 

  return true;

}