code: public String readString(HKey hk, String key, String valueName) throws RegistryException {
  		return readString(hk, key, valueName, null);
  	}
docs: Read a value from key and value name
  
  @param hk the HKEY
  @param key the key
  @param valueName the value name
  @return String value
  @throws RegistryException when something is not right