function validate_form ( )
{
  valid = true;

  if ( document.form121.fname.value == "" )
  {
      alert ( "Please Enter 'First Name'." );
      valid = false;
  }
  else if ( document.form121.lname.value == "" )
  {
      alert ( "Please Enter 'Last Name'." );
      valid = false;
  }
  else if ( document.form121.telno.value == "" )
  {
      alert ( "Please Enter 'Tel number'." );
      valid = false;
  }
  else if ( document.form121.email.value == "" )
  {
      alert ( "Please Enter 'Email'." );
      valid = false;
  }
  else if( document.form121.email.value !="")
  {
      var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
      var email=document.form121.email.value;
      if(reg.test(email) == false)
      {
	alert('Invalid Email Address');
	valid=false;
      }     
  }
  
  return valid;
}